The C2A1 is Threaded in 40mm (specifically; It uses the Rd40 x 1/7″ thread (NATO Standard), Making it Compatible with most Gas Masks, Particularly all Current NATO Gas Masks.

This Production C2A1 Filters are Sealed in a Tin Can to keep the Filter Components Fresh and Unexpired.

These Canisters are Manufactured with  Impregnated Carbon which Offers Increased Protection against Chemical Agents.

The C2A1 DIN Threaded Canister is Intended to Reduce Exposure to Chemical and Biological Warfare Agents and is used by the United States Military.

C2A1 Canister Protects the User From Up To 15 Nerve, Choking, Blister Agent Attacks, and Two Blood Agent Attacks.

When used with the M40 face pieces, this Cartridge is NIOSH Approved for Protection from Sulfur Dioxide, Chlorine, Hydrogen Chloride, Chloroacetophenone (CN), O-chorobenzylidene Malonitrile (CS). It can also Filter Solid and Aerosol Liquid Particulates (Oil and Non-Oil Based) and Adsorb a Wide Range of Chemical and Warfare Agents Including Nerve Agents – Tabun (GA), Sarin (GB), Soman (GD), VX; Mustard Agents – H, HD, L; Tear Agents – CN, CS, OC; Blood agents – Hydrogen Cyanide (AC), Cyanogen Chloride (CK), Arsine (SA); Choking Agents – Chlorine, Phosgene, Chloropicrin (PS), and Diphenylchloroarsine (DA).