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The M2 was a French gas mask used in the first world war. It was massed produced from 1916-1918 as one of the most common French gas masks in the war, which there was the M2, (this one) The ARS-17, a canister design to later Be updated to the TC-38 in Ww2, and the Tampton Mask, which was used earlier and saw combat use through 1915-1916. These are the masks that are coming out soon as a Project.
