The events of 9/11 as they unfolded through actual audio.
1962 Respirator for Tank Crew
The need for a collective protection system for tank crews resulted in the development of the M14 Tank Mask in 1953. The facepiece was made of molded rubber in three sizes with a single plastic lens. A hose connected the mask to the air purifier and a cable connected a microphone to the tank's communication system. A standard canister was available when the mask was disconnected from the three-man collective protection system. Starting in 1952, the Chemical Corps began work on a new mask to replace the M9 series. The corps wanted a mask that was more reliable, suitable for any face size and skin texture, and more comfortable in any climate.