The M2 mask was used by the US Army, replacing the M1. The M2 was developed and used during the second world war, from 1941, to 1949.
In 1939, the US Army developed the lightweight M1 Training Mask with a fully molded rubber facepiece, the first mask to eliminate stockinet cloth coverings by taking advantage of improved rubber. The M1 Training Mask was standardized as the M2A1 Service Gas Mask in 1941.
As the training mask it used a cylindrical canister attached directly to the facepiece at the inlet valve, projecting downward to the wearer's chest. The M1 Training Mask was carried in a deep-pocket shoulder bag with a snap opening at top and a waist string attached to D-rings.
The M2A1 Service Mask used the facepiece of the training mask but replaced the training canister with the corregated tube and M1XA1 filter canister arrangement from the M1A2 Service Mask.
Based on experience with the M1A2 mask, the M2 Service Gas Mask was produced in three sizes: small, universal, and large. Improvements to the outlet valve resulted in the M2A2 in 1942 and the M2A3 in 1944. The M2A1 outlet valve was flat, egg shaped with no grill. The M2A2 and M2A3 had a round outlet valve with concentric circle grillwork.
M1VA1 Gas Mask Bag, used for the M1 and M2 series masks and others, sometimes with additional markings to designate which mask is enclosed. The "U" indicates the size.
The M2 mask was very successful in providing protection for the soldier, but weighed about 5 pounds and was too bulky and inconvenient to use. The next design, theM3 Lightweight Gas Mask, made substantial improvements over the M2 series.
The M1VA1 carrying bag was used with a wide right-shoulder strap, carried at waist position on the left side. In use, the mask was removed from the bag while the canister remained in the bag, connected by the hose. A waist strap kept the bag close to the body.
The M2 series masks lacked an internal nose cup and therefore were prone to fogging. That problem, and its heavy canister, led to the development of the M3 series and M4 series Lightweight Service Gas Masks during 1942. Over 8 million of the M2 series masks were produced during World War II, becoming obsolete in 1949.