Gas Mask and Respirator Wiki

The M9 Series Field Protective Masks are some of the most successful gas masks to be used by the United States military, derivations being adopted by at least six other countries. Starting production around 1947, the M9 Series remained in standard infantry service until the early 1960s, when it was phased out with the introduction of the M17 Field Protective Mask .

Despite being replaced as a standard infantry mask by the M17 Series during the early/mid-Vietnam War, the M9 series continued service with National Guardsmen and Law Enforcement (even though they had specialty gas masks of their own) during protests against the war. It was also issued to Civilian Defense workers and civilians alike, and the M9 series would be used by these organizations up until the 1970s.

Even after the M9 series was phased out by general infantry, policemen and civilians alike, it continued its use by the U.S. Heavy Decontamination Crews, Chemical Stockpile Inspectors and Handlers, and EOD Personnel used the mask from its conception in the late 1940s until the early 1990s as a part of the ABC-M21 Rocket Propellant, M15 Compressed Air Breathing, Toxicological Agents Protective (T.A.P.) Gear ensembles.


By late 1944, the U.S. military had multiple standard service masks in use, including, but not limited to - the M3/M3A1 and M4/M4A1 Lightweight Service Masks, and the M5 Combat Service Mask. It was justifiably decided that the M3/M4 Lightweight Service Masks were too bulky in comparison to the M5 Mask and that the full adoption of an "Assault-Type" service mask would be the best possible outcome, however the complications in mass-producing the M5 and its poor handling of below-zero climates lead the CWS into investigating alternative manufacturing methods and designs to replace the M5. Suspecting a full-scale invasion of the Japanese home islands was imminent, the first step taken towards supplying the Pacific Theater of Operations with "Assault" Masks was the M8-11-10 Snout-Type Service Mask.

An extremely early prototype for what would eventually become the M9, seen at the Chemical Warfare Museum Archives, Fort Leonard Wood, MO. Its designation is at the moment, unknown, and given its crude nature of construction, it could not have been developed any later than 1944. Photo credit to Bart Wilkus.

The M8 was little more than a standard M3 or M4 Series Lightweight facepiece with an upgraded C4 Head Harness and a metal angled 60mm thread assembly attached to the stem the M3 Hose had previously occupied and served as a stop-gap design to issue while development continued on improving a new side-canister mask. The CWS Division at the Massachusetts Institute of Technology, which had previously developed the M5-11-7, was now dealing not only with how to improve the means of effectively molding a side-canister mask but also to produce them of a suitable artificial rubber which was as resistant to extreme temperatures as it was to chemical agents. One of the first developments which began to show promise was a drastic modification to the M3 faceblank design, which had a deflector channel that ran over the nose pocket, rather than cutting into the pre-existing vertical deflectors.

The prototypes which followed along this general design pattern were known as the E19 Series Combat Service Masks. These prototypes varied and progressed in development well into 49 revisions. Perhaps the most well-documented example was the MIT-E19R25-M11 Combat Service Masks, which were given a full report on March 7, 1945.

MIT-E19R25-M11 Combat Service Mask[]

IMG 2552.jpg

The mask which had been developed had a solid injection-molded faceblank utilizing a black butyl rubber compound which was both far more chemical and weather-resistant than neoprene, a C15 Outlet Valve, and a 60mm threaded filter inlet stem for the M11 Combat Canister. Like the M5-11-7 Combat Service Mask, this thread assembly attached to an port on the side of the facepiece, however unlike the M5, this port was molded as a part of the faceblank as one piece, leading to the molded-in "mustache-type" airflow deflector channels, which wrapped over the 'nose pocket' of the faceblank and ended under each eyepiece. This gave the mask a rather humorous appearance of having a large, comical-looking nose while also being much more effective at clarifying the lenses and being much easier to produce.

Inside the mask, there was an oronasal cup, which was improved over the types used on the M3 and M4 Series Lightweight Masks - this was because the E19's oronasal cup curled in, as opposed to curling out, which gave it a better seal. The mask also utilized new, improved laminated glass eyepieces (MIT-E2) with thicker aluminium eye-rings (MIT-E1R10) over the older steel-framed, cellulose acetate eyepieces. Like the older M5 Combat Service Mask, the MIT-E19R25 (as well as most of the E19 Series Prototypes) used the C4 Head Harness Assembly, which included a nape strap to support the canister.

There were two main variants of the MIT-E19R25-M11 - the E19R25 and the E19R25-F (Featherweight). The main difference is the carriers issued and minor construction details on the inlet valve. The E19R25 was issued with the MIT-E19R2 Combat Carrier, a compact, boxy OD cotton duck canvas bag with a roll-flap closure and an extended indent in the profile to accommodate the canister.

The E19R25-F was issued with the MIT-E20 Combat Carrier, an even smaller, rectangular pouch which was supplied with the standard M1910 Wire Hook Hanger on the back to suspend the carrier from the cartridge belt. In addition, the kit also had a water-resistant inlet valve, weatherproofed M11 Canister, and a canister waterproofing plug kit and instruction card.

MIT-E19R2 Combat Carrier MIT-E20 Combat Carrier M7A1 Carrier Canister Plug Waterproofed Inlet Valve
MIT-E19R25 Yes No Yes No No
MIT-E19R25-F No Yes No Yes Yes

MIT-E19R2 Combat Service Carrier[]


The main carrier assembly issued to the MIT-E19R25 was the MIT-E19R2 Combat Carrier, noted by its construction of water-resistant OD cotton dock, lopsided shape to accommodate the M11 Combat Canister on the mask, and its roll-flap closure system, which was fastened by two 'Lift-The-Dot' Fasteners, as stated previously. The carrier also featured removable carry straps and internal pockets for the Anti-Dim Stock or Cloth, the M1 Eyeshields, M5 Protective Ointment, and two Individual Gas Protective Covers. The E19R2 Combat Carrier was noted for its convenience and how it allowed the quickest donning times of the mask when compared to the E20 and M7A1 Carriers, however, it was noticed that soldiers would often incorrectly roll the carrier opening gusset closed and that the accessory pockets often interfered with removing and replacing the mask.

With the addition of snap fasteners to the inner accessory pockets, the speed of removing the helmet, removing the mask from the carrier, donning, clearing, sealing, fastening nape strap, replacing helmet and closing the carrier was increased from 23.0 seconds without snap fasteners to 19.7 seconds with. However, it was found that the E19R2 Carriers caused the facepieces to take on a permanent set cease near the chinpiece during long storage periods, and generally had very poor water resistance, with all tests proving that the carriers would become flooded when immersed no matter how tightly the roll. Reports state that a longer roll-flap closure similar to the M7/M7-A Carriers were being researched.

MIT-E20 Featherweight Combat Service Carrier[]


The carrier bag issued with the MIT-E19R25-F Mask was the MIT-E20, a small, rectangular carrier made of OD103 Canvas Duck Fabric with a single flap closure at the top, fastened with 2 'Lift-The-Dot' Fasteners, and removable carry straps, similar to the E19R2 Carrier. Unlike the E19R2, the E20 Carrier had an M1910 Wire Hook to suspend the carrier from the user's cartridge belt, and no internal accommodations for the Individual Gas Covers, Eyeshields, or Protective Ointment. The only internal pocket was a small sleeve on the lid for the anti-Dim cloth.

Additionally, the mask had to be stored inside with the canister removed and sealed with the waterproofing plug set issued to the E19R25-F Kit, quite reminiscent of how the British Light Anti-Gas Respirators were stored. Due to this, the E19R25-F Masks had the slowest drill time (35.2 seconds), due to being stored with the filter plugged and unscrewed from the facepiece. These extra steps also required additional drill procedures to tore the mask in 'alert' or 'sealed' configurations.

The E20 Carrier also had absolutely no waterproof capabilities, needless to say, and tests showed that even in rainy conditions, it was not uncommon for the E20 Carrier to become flooded. Despite the highly-praised, extreme lightweight of the E19R25-F Gas Mask, its concept was ultimately deemed unsatisfactory due to inconvenience in donning and lack of accessories. The MIT-E20 Carrier would cease development shortly after.

M7/M7-A Combat Service Carrier[]


The M7-A Combat Service Carrier is little more than a slight modification to the M7 Carrier used with the M5-11-7 Army Combat Service Mask. It is a large, semi-hexagonal carrier made of cotton duck canvas coated on both sides with black butyl rubber. The side opening is secured with a roll flap and a row of 3 'Lift-The-Dot' Fasteners.

The main and only difference between the M7 and M7-A is that the former has its straps permanently sewn on to the carrier body, whereas the M7-A is supplied with 4 grommets to allow removal of the straps via standard snap-hooks. Improvements to the butyl rubber coating made the M7-A less reflective as well when compared to the standard M7 Carrier. The M7-A Carrier was appreciated for its roominess and its totally waterproof design, more than capable of holding the E19R25 Mask, with attached M11 Canister, and all authorized accessories.

The time needed to don the mask was, however, slow (31.5 seconds for the M7-A, and 25.6 seconds for the M7) due to the rolled opening gusset taking up time, and additionally, the non-reflective butyl used on the M7-A was tackier than the shiny rubber coating used on the M7, owing to greater friction as the mask was pulled out. The carrier was also disadvantageous for its great size when compared to the E19R2 and especially E20 Carriers, and reports showed that men preferred the M7/M7-A Carriers the least in all situations.

Additional problems also included cases where the rubber coating was susceptible to wearing away from field abrasion, and complaints of the snap-hook and grommet removable carry straps were inconvenient to fasten. Nevertheless, reports concluded that the original M7 Carrier was the best of all carrier designs trialed for the E19R25 and E19R25-F Masks, and work began on improving the materials and construction of the M7 Bag to correct the previously noted flaws.

M9 Gas Mask/Field Protective Mask[]

An M9 Field Protective Mask with early C48R1 Facepiece (Left) compared to the older M3-10A1-6 Lightweight Service Mask. Notice the later pull-tab on the C15 Exhale Valve.

The E19 Series was noted for its great improvement in comfort, durability, range of visibility, and better handling in colder temperatures, and so sometime in December of 1947, the MIT-E19R49-11-15R1 Combat Service Mask (a.k.a. 'E48R1'/'E49') was reworked and finalized as the C48R1 (Contribution (or 'Component') 48, Revision 1) Facepiece for the M9 Gas Mask kit. The C48R1 Mask was not very different from the E19 Series, as they both used generally the same mold pattern, same laminated glass and aluminium eyepieces, and same inner oronasal cup. The main notable differences from earlier prototypes were that the faceblanks began to get molded from a white natural rubber as opposed to black butyl (likely done as a result of how butyl expensive is to produce and the regained access to natural rubber supplies postwar), the C15 Valves used on the C48R1 eliminated the sleeve extension behind the rubber shroud, and later variants included a pull tab for easy removal in arctic weather.

Another change that took place leading to this mask was changing the "Universal" size to "Medium", as well as upgrading the earlier C4 Head Harness to the newer C8. The C8 head harness had a rectangular head pad made of thick, grey (later black) cotton duck fabric, similar to the MIIA1 Harness, as opposed to the black or sage green triangular vinyl fabric head pad of the WWII C4 Harness. Like the C4, the C8 also utilized a nape strap that was intended to prevent the weight of the canister from shifting the mask on the face.

C15R1 Carrier[]

The C15R1 Carrier.

The C15R1 (also called 'M7A1') Carrier, which was remarkably similar to the M7 Carrier, was the approved carrier design issued with the M9 Kit. It followed the same design pattern and relatively the same dimensions as the older M7, except that the C15R1 was made of OD107 Cotton Duck Fabric, which was rubberized only on the inside, as opposed to being completely rubberized inside and out like the M7. After the M9A1 Field Protective Mask was introduced, only the USMC continued to exclusively use the original M9 Field Protective Mask with the C15R1 Carrier.

Changes and Improvements[]

A typical M9 Field Protective Mask.

Initially on, 'M9' was the kit designation and 'C48R1' was the Facepiece designation, departing from the WWII-era 'Mask + Filter + Carrier' Designation System, however by 1951, the designation 'M9 Field Protective Mask' was adopted and altered to not only refer to the kit, but the facepiece as well. Not long after this designation pattern was introduced, the black butyl rubber C48R1 faceblanks and C15 outlet valve shrouds began to diminish in favor of those produced of white natural rubber as the U.S. regained its access to sources of natural rubber stocks. By 1952, Butyl M9 Facepieces had stopped production entirely.

The M9 was perhaps the most versatile protective mask in U.S. military history, serving as a standard-issue infantry mask from the Korean War well into the Vietnam War periods and continued to emerge as a special-purpose mask long after being phased out of standard service. The mask could also be produced with the canister on the left or right-hand side to accommodate different-handed riflemen (a feature that was abandoned on the M5-11-7 Combat Service Mask), and over 3 million facepieces were procured before it was declared obsolete as a standard infantry mask in the early 1960's.

M9A1 Field Protective Mask[]

A typical M9A1 Field Protective Mask with spare M11 Canister and Packing Tins.

Also sometime around 1951, the M9 was given another upgrade - as it was realized the principles of an 'Assault'-style gas mask used primarily for amphibious landings and airborne missions was growing obsolete, the need for an all-encapsulating waterproof carrier was also becoming obsolete. The M9A1 changed nothing in regards to the kit except for the carrier, now replaced with the more compact E18R9 (M11) Carrier Bag, which allowed quicker access to the mask and adequate convenience of carrying. The lightweight and accessibility of the M9A1 became so popular that production quickly overtook the M9, with packing tins marked for M9 Field Protective Masks hastily being painted over and re-stamped to contain M9A1's.

The standard packaged accessories for the M9/M9A1 Masks consist of:

M11 Canister C15R1 Carrier M11 Carrier Anti-Dim Cloth Packed in Cardboard Box Packed in Metal Tin
M9 Yes Yes No Yes Yes Yes
M9A1 Yes No Yes Yes No Yes

Additional issued accessories include:

M5/M5A1 Protective Ointment and Atropine Kit ABC-M4 TAP hood M1 Waterproofing Bag M8 Chemical Detector Paper
1 Issued 1 Issued, Optional 1 Issued 1 Issued

E48R10 Combat Service Mask[]

E48R10 and M9A1 Field Protective Masks, 1953.

Shortly after production increased on the M9/M9A1 Series Masks, it was realized that with the ever-growing communist influence throughout East Asia, it was quite possible that like Japan had done during the Second World War, another enemy nation in this region may attempt to cut the U.S. off from natural rubber supplies. It was established that Butyl, which excellent in inclement temperature resistance and chemical protection, was far too expensive to procure on such a massive scale, so in 1952, a small experimental batch of M9A1 Masks were procured in black styrene rubber to begin testing and evaluation as the E48R10 Combat Service Facepiece on June 17, 1953. The object of this testing was to evaluate whether the black styrene rubber could hold up to the same standard and requirements as the natural white rubber M9A1 facepieces, should natural rubber imports be cut off and a need arise for the U.S. to produce its own artificial rubber.

During initial, uncontrolled tests, 32 complaints regarding comfort were obtained out of the approximately 103 independent trials with 23 men. 14 out of these men claimed the rubber would stick to the skin, cause irritation, and was generally less comfortable than the M9A1. Climate-related tensile strength, mask weight, and user handling were found to be near-identical to the M9A1.

When tested for liquid agent penetration, it was found that the E48R10 took 4-5 hours for GB Mustard to penetrate while the M9A1 took only 3. Despite all further testing, it was omnipresent that the styrene rubber of the E48R10 proved too much of a general discomfort to most test participants, as it would stick to skin within 10 minutes of donning at ambient temperatures, however less complaints were received during climate testing. It is noted that upon doffing the mask, test subjects would need to grasp the facepiece at the edge to physically peel the rubber from their skin, however no burning/irritating aftereffect was noticed.

It should be noted that during this early test phase, the E48R10 was visibly distinguished from the M9A1, perhaps leading to some bias among the test subjects of the experimental design. Later testing proved this theory, as groups of 4 men each with E48R10 and M9A1 Masks, the former being disguised as M9A1, 3 out of 4 men could tell no difference between either mask. It was ultimately decided that the E48R10 was suitable as an interim stop-gap should the procurement of natural rubber stocks become unavailable.

On the collector's market, the E48R10 exists in very few numbers. Being an experimental mask, they were procured in very small quantity, and most were destroyed after they were no longer needed. 4 Specimens are known to exist in the collections of Pixelproductions100, Jojo Uy, the late Uwe Rosenfeld (Atemschutzddr), and an unknown collector, and while they may be mistaken for earlier Butyl E19/E48 Masks, they can be distinguished by the presence of 1952-53 date stamps and a white C15 Exhalation Valve Cover.

M11 Carrier Bag[]

M11 Carriers, both regular and 'Special Purpose'-marked. From the Collection of GasMaskBunker.

The M11 (E18R9) was the standard-issue carrier bag for the M9A1 Field Protective Mask, made of an OD107 water-repellent cotton duck canvas. It is a flat bag measuring 9½ by 12 by 4½ inches, opening with a reinforced flat closure retained by 3 'Lift-The Dot' Fasteners. Two pockets are provided on the interior bottom and side for the Protective Ointment Kit and the M1 Waterproofing Bag.

The Anti-Dim Cloth is retained in the upper back of the carrier with a loop of fabric. Markings on these carriers varied greatly throughout its production run, however, all were typically stamped with the usual "US" and Chemical Corps Logo, with 'Field Protective Mask, M9A1' marked below. And below this, the mask's size and canister position letters (for instance ML = Medium Size, Left Canister Stem) were boldly marked.

As the M9A1 began to get demoted as a special purpose gas mask, M11 Carriers were procured beginning sometime in the 1970s or 80s which read 'Mask, Chemical-Biological, Special Purpose, M9A1' without any information regarding the size or the canister stem being present. These special-purpose carriers are very uncommon and are occasionally found on their own most times, as they were likely procured as a replacement part, rather than issued with newly-packaged M9A1 Kits.

C15 Exhalation Valve[]

C15 Valve Variants.png

Implemented in 1944 to atone the shortcomings of the older MI, MII, MIV, MV, MVI, and M8 Valves, which were prone to becoming jammed with mud and frozen over in arctic operations, the C15 Exhalation Valve was the most successful and long-lasting outlet valve design in American history. It consists of a die-cast metal seat, the rubber valve disk, and the rubber shroud assembly, which included molded cleats on the interior to assist in de-icing the valve without disassembly.

  1. The Late 1944 Pattern C15 was introduced with limited procurement for converting M3 and M4 Lightweight Service Masks to the M3A1 and M4A1, respectively. It could also be seen on variants of the M5 and M8 Service Masks as well as the E19/C48R1 Facepieces, which would later become the M9. According to TM 3-205 (1955), some M9 Series Masks could be found issued with this pattern of valve. It is identified by its black butyl rubber shroud, which lacks the signature pull tab and manufacturer's clock.
  2. The 'Transitional' Pattern C15 was little changed from its WWII counterpart, with the main and only deviation being the introduction of a textured pull tab to easily remove the valve shroud while wearing the mask. These were seen on later variants of the C48R1 Facepiece between 1948 and 1950.
  3. The Standard Pattern (White) C15 is the most easily recognizable of all variants for its distinctive white rubber and manufacturer's clock stamps on the front. All issued M3A1, M4A1, M9/M9A1, M13, and M14 Series Masks plus many others used this valve. It was not put out of service until the M9 Series became officially obsolete entirely from EOD/Special Purpose use in the early 2000s.
  4. This black variant of the Standard Pattern C15 was first introduced on the M24 Aircraft, M25A1 Tank, and M13A1 Headwound Masks and was made of a natural rubber/hycar blend. This valve is otherwise unchanged from the previous design but is still well in use to this day as older stocks of M13A1 Hospital Headpieces continue to be issued to this day.

ABC-M15 Compressed Air Breathing Apparatus[]

M15 Compressed Air Breathing Apparatus.jpg

One of the many configurations the M9 Facepiece could be found in was the M15 Compressed Air Breathing Apparatus, an early Self-Contained Breathing Apparatus (SCBA) Unit. The M15 Was used for odd special-purpose duties where the life of an air-purifying canister would be exhausted too quickly, or simply not effective. The setup was most commonly seen in the hands of missile refuelling crews, such as those tasked with fueling the MIM-3 Nike Ajax Missiles.

The kit was essentially a standard M9 Facepiece with a corrugated hose, 60mm threaded on the mask end, and connected to a demand regulator with a right-angled elbow. Two large steel canisters on the back supplied air to the regulator and mask. The kit is stored in a large green fiber trunk and typically worn with a rocket propellant suit and a hood or an M1 Winterizing Kit.

ABC-M21 Rocket Propellant Gas Mask[]

An ABC-M21 Rocket Propellant Mask from the Collection of Bart Wilkus. Missing the Carry Sling in this photo.

Finalized off the E15 Rocket Propellant Gas Mask, the ABC-M21 is a standard M9 Facepiece with a 60mm-threaded, 27" Hose (Designated MIIA1) with a right-angled, 25mm-threaded elbow on the other end to accept a Willson (E15 Only) or MSA GMN-SS (M15) Rocket Propellant Canister. The canister was carried in a green faux leather carry sling and the mask was typically furnished with an M1 Winterizing Kit. The whole kit was stored in a green fiber carry trunk, similar to the ABC-M15.

As the name would imply, the ABC-M21 was developed for rocket refuelling crews dealing with volatile and highly toxic chemicals in addition to potential liquid oxygen exposure (hence the winterizing kit). The kits seemed to have lasted well into the 1980s, alongside other kits such as the M26A1 Rocket Propellant Masks and were typically utilized by Nike Ajax and other similar missile handlers.

Toxicological Agents Protective Ensemble[]

The TAP Ensemble with M9A1 Masks, M3 Hoods, M3 coveralls, M2A1 Boots, and M1 Boot Covers seen in Use. The Man on the far right wears an M17A2 Mask and older CPOG Suit.

One of the longest-lasting uses of the M9 Facepiece in the U.S. military was as a part of the Toxicological Agents Protective (TAP) Ensemble which saw the mask used from 1953 until 1995 (or later!). The setup consisted of M9A1 Mask, M11 Canister (Special-Purpose Designated Production after 1980), Special Purpose M11 Carrier (Special-Purpose Designated Production after 1980), M3 Hood, M3 Impermeable Coveralls, Impermeable Gloves, M2A1 Boots, M1 Overboots, and Chemical Protective Undergarments. It was a setup specially designed and utilized by munitions handlers/inspectors, decontamination and EOD personnel, and military laboratory teams.

Much like previously-listed kits relating to the M9 Facepiece, only the accessories, filters, and carriers are different while the facepiece is a standard M9.

Additional Accessories[]

ABC-M4 Toxicological Agents Protective Hood[]

The ABC-M4 TAP Hood worn on various masks.

Many 'Leakproof' Gas Mask Hoods were developed during the late WW2 period, and the one that ultimately got far was the E40R9 Impermeable Protective Hood, later finalized as the ABC-M4. It was made of olive drab or white cotton fabric that was coated on one side with green butyl(?) rubber. It was supplied with two openings for the eyepieces with inner drawstring seals, a neck drawstring and plastic slider assembly for a seal, and a sleeve that fit over the canister.

The hood came in a small storage pouch that was made of the same rubberized fabric, and was intended as a standard protective hood to replace the older WWII Poplin Gas Hoods. While designed primarily for the M9 Field Protective Mask, they were also able to be used with older M8, M5, M4 and M3 Service Masks that were still in circulation until 1958.

M3 Toxicological Agents Protective Hood[]

The M3 Toxicological Agents Protective Hood. From the GasMaskBunker Collection.

Similar in design and pattern to the ABC-M4, the M3 TAP Hood was made of a thicker, dual-coated butyl rubberized fabric material with tape cemented over the seams to prevent leaks. The hood also boasted an inner neck flap (which retained the drawstring), and underarm straps which secured the hood in place. Like the ABC-M4, the outlet valve was contained inside the hood, so positive pressure would inflate the material and keep chemical agents from entering.

Despite both sharing the Toxicological Agents Protective Designation, only the M3 was used with the TAP Ensemble, more specifically with the M3 Impermeable Coveralls. A later variant of this hood was also designed for use with the M40 Series Field Protective Masks. The M3 Hood continues service with chemical munitions handlers to this day.

Toxicological Agents Protective Cooling Hood[]

The Cooling Overgarment Hood for the M3 and M3A1 TAP Hoods.

Due to the lack of an integrated hydration system on the M9 Facepiece, it is very easy to contract heat stroke while wearing the Toxicological Agents Protective Ensemble. One solution to the inherent heat of the equipment came in the form of special, disposable cooling overgarments. Made of thin fabric, they were soaked with water and donned over the suit, with the idea that the evaporating water causes an intense chilling effect to prevent the user from overheating in the suit.

The cooling overgarments consisted of a jacket, trousers, and hood that fastened onto loops on the M3 TAP Hood. The overall effect that these garments had was negligible but effective enough to remain in service.

M1 Winterizing Kit[]

The M1 Winterizing Kit (Missing the Insulating Lens Inserts). From the GasMaskBunker Collection.

Following the end of WWII and the beginning of the Cold War, the U.S. Army realized that if it were to potentially fight on Eastern European soil, it would seriously need to evaluate the downfalls of their current protective masks. The M3, M4, M5, M8, and M9 series masks currently in service proved to be unsatisfactory for cold weather climates, as the faceblanks would begin to stiffen at -28°F (-28°C). To counter this, several various arctic hoods and headpieces were considered, resulting in the M1 Winterizing Kit.

The kit was a peculiar and ingenious butyl-coated nylon chemical hood that was engineered to the point of redundancy. The outlet valve of the mask was isolated in a double-walled pouch that vented the warm, exhaled air back into the hood while a watertight zipper allowed the user to remove excess moisture and blocks of ice formed from the condensate. The hood also had pouches that allowed it to fold up and serve as its own carrier as well as pouches for additional winterizing accessories for the mask.

These accessories included a fleece forehead pad to prevent icing of the sweat, a set of anti-snow glare lens outserts, a set of insulating lens inserts, an inner cheek pad to prevent the metal canister threads from causing frostbite on the user's cheek, a set of spare nosecup valve disks, and a manual. As the M9 series masks began getting phased out by the mid-1960's, as too did the M1 Winterizing Kit, but much like the M9, it continued to live on as a piece of special-purpose chemical gear.

Corrective Optical Lens Inserts[]

Late Pattern Corrective Optical Inserts for M9/M9A1 Masks. From the GasMaskBunker Collection.

Soldiers who required corrective lenses to do vision defects were supplied with a pair of optical inserts, a set of spring frames that fit inside the standard semi-triangular eyepieces of American gas masks and retained a set of prescription lenses within. These inserts had been in service since WWII and had carried over into the M9 Series. In the 1980s, a new type of optical inserts for the M9/M9A1 Special Purpose Masks was developed, patterned closely off the inserts designed for the M17 and M40 Series Masks.

Finding optical inserts for M9 Series Masks and earlier can be somewhat of a difficulty, as most were likely collected and re-issued to another soldier after they were no longer needed on one man. Finding the late pattern is even more of a rarity, as they may have been a custom-made item from excess stocks of XM40 or M17 Optical Inserts.

Foreign Variants and Users[]

Finland: M/61 - made of grey rubber, and manufactured by Nokia with three different models:

  • Model 1 - Most similar to the U.S. M9. The only changes were the use of M17-style harness buckles, the addition of a Nokia manufacture mark on the filter side, and 'SA' (Finnish: Suomen Asevoimat "Finnish Military") replacing 'US' at the top.
  • Model 2 - This version has a longer outlet valve cover, and a peripheral seal was added. The 'SA' marking was removed, and the watchtower of the Finnish Defense Forces was added on the opposite side to the filter.
  • Model 3 - Final, most common model. The rubber exhalation assembly was replaced by a black plastic assembly, incorporating a voice diaphragm, the cover featuring the distinctive watchtower of the Finnish Defense Forces.

Sweden: Skyddsmask 51 - Similar in appearance to the M9A1, made of dark green rubber or sometimes white rubber, has a similar outlet valve cover to the second model M/61.

Norway: NM16 - This mask was was identical to its Swedish counterpart and differed only in its thread, which was a NATO 40mm thread.

Japan: JSDF Type 2 Protective Mask - A fairly distant, but somewhat similar copy of the M9/M9A1. Made of light olive drab rubber, lenses are more rounded, the outlet valve is a metal cage-type or occasionally a loose C15 Clone. These masks are very rare outside Japan.

South Korea:

  • M9A1 - South Korea initially used American M9A1 Masks for much of the 1950s well into the 1970s before they began producing domestic copies.
  • KM9A1 - Made of black rubber, similar to the C48R1. Very rare, but somewhat more common than the Japanese type. Often found as specimens issued to Iraq and other forces in the Middle East - these are commonly mislabeled as 'Bulgarian' M9 copies due to the rough assumption myth started by 1st Generation Collectors because of the M10 clone produced by the same country. There is no logical evidence these are Bulgarian-made as they share no hardware or design patterns coexisting with period Bulgarian mask designs, and Iraq was commonly issued South Korean-produced equipment.

Yugoslavia/Serbia: M-1/M-2 Series - Made of an aqua-ish green rubber, the M-1 had a similar carrier bag to the M11, and was the military counterpart of the MC-1, which had no oral-nasal cup, had "MC-1" stamped on the left side of the mask in black, also had a cheaper carrier. The M-2 was made of the same color, but higher-quality rubber, and was basically was an update of the M-1. It had black plastic frames instead of the green metal of the M-1. A variant called the MC-2 had a drinking feature. The M-2 had two different types of outlet valves - one that was a plastic cage, and one with a green deflector. A model called the M-2-F was made of all black rubber and had black parts, and resembled the Finnish Nokia M/61 (third model), for it had a similar outlet valve/voice diaphragm assembly. The M-2FV was the same but had a drinking device.

Egypt: M2 - Licensed exact copy of the Yugoslavian M-2, made of black rubber and plastic.

Iraq: Uses the South Korean KM9A1 and the Yugoslavian M-1 (renamed the M-65).

Italy: A large number of M9A1s were shipped to Italy, and used to an unknown degree by the Army and the Red Cross. These masks were occasionally used for training by the Red Cross well into the 2000s, with the latest recorded instance being 2012 [1]; this is probably due to the lower funds of the Red Cross.



  1. Mask History - Infantry or General-Purpose Mask by Major Robert D. Walk
  2. Italian Use of the M9 Mask
  3. Technical Manual 3-205 - Protective Masks and Accessories, April 1955
  4. Technical Manual 3-205 - The Gas Mask, March 1951
  5. Technical Bulletin 3-205-2 - Winterizing Kit, Protective Mask, M1, March 15, 1957