While most modern masks use 40mm threaded filters, some older masks use the less standard 60mm threading. The difference between the two basically boils down to compatibility, since the 40mm became much more common. Some notable gas masks that use 60mm threading for the filter intake are:
-The US M5 assault mask
-The US M9a1 and its many copies:Yugoslavian M-1, Finnish M-61 and others] (The 60mm threaded filter for the US M9a1 and other 60mm threaded masks was named the M-11 filter canister, the official designations for the Yugoslavian and Finnish filters is unknown.)
-The Canadian C-3 gas mask
- The US CD V-800 Civilian Mask
Since 60mm threaded filters are relatively few in number, these will be grouped into a single article.
Suodatin 61EditThe Suodatin 61 filter canister is a 60mm filter canister which was issued alongside the Finnish M-61 mask, grey in color to match the the mask itself. Just as the M-61 is most likely the easiest [and therefore in many (but far from all) cases cheapest] 60mm gas mask on the surplus market, so is the accompanying filter the easiest 60mm threaded one to find. These were manufactured until about 1992, and as such all filters are almost certainly expired. The Suodatin 61 filter canister is easy to distinguish due to the markings on the filter, as can be seen in the picture to the right. We are unfortunately not 100% sure if these filters contain chromium we do not have any sorts of data or statistics documents on this so it remains a mystery until there is legit proof by the company itself or a lab confirming it.
US M-11 Filter CanisterEdit
The US M-11 filter canister was used first with the US M5 assault mask, afterwards the US M9 and M9a1 gas masks, as well as the M13/m13a1 headwound gas masks. It, like the Finnish canister, is grey in color, but unlike its Finnish counterpart is much more plainly marked in ink with the serial/lot number, and other markings stamped into the metal. [Authors note: I have not seen one of these filters in person and may be mistaken]. These filters are less common than the Finnish canisters, but are by no means difficult to find should one search for them. The filters were in production from the 1940s to the 1980s, though it should be noted that production was likely cut by an unknown but most likely significant amount after the M9a1 was phased out of service by the general infantry in 1959. The M9 masks were still being used up until the 90s [by decontamination crews, the national guard, and for other uses], and as such there was a (albeit limited) need for the M-11 filter to be produced for an extended period. It is interesting to note that the continued production of the M-11 filter was used instead of a filter adapter, probably because it was for the time period much more practical.
Canadian C-3 Filter Canister*Edit
These filter canisters were used in canadian gas masks until the C-4 (which has a 40mm thread) replaced the troublesome C-3 model. An interesting thing to note is that as the Canadian Armed Forces moved towards the 40mm threading system for filters, they implemented a 'stop-gap' measure before the C-3 was fully phased out of service. This came in the form of a device which served as a 60mm to 40mm adapter, meaning that it allowed 40mm canisters to be used in a 60mm threaded mask. These are simple plastic pieces with rubber gaskets to ensure proper seal, and can be found on the surplus market for maybe $8 each. They were manufactured in both orange and black.
Yugoslavian M-1 Filter Canister*Edit
These 60mm canisters were made in former Yugoslavia for the M-1 gas mask [which was essentially a copy of the US M-9 gas mask]. The canister is a pale green, matching the mask's OD green look. The only markings on the filter are the serial number, which shows the manufacture date and lot number. These filters are not often sold seperate of the mask kits themselves, though the kits are not particularly rare or expensive. As such, replacement filters at a good cost for this mask are few and far between, though it will work with any 60mm filter [or 40mm filter with the Canadian 60-40mm adapter].
*The official designation of these filters is unknown, and is thus labeled for the mask best known to use it.