The British SR6 gas-mask more commonly called the S6 was used from the late 60s to early 80s by the British armed forces and special forces. The mask takes a side loading 40mm filter and has lenses that are curved to allow peripheral vision. The mask features a tube which allows the mask to inflate to form an airtight seal if the straps are not adjusted properly. The mask was made by both Avon rubber and Leyland and Birmingham rubber.