U.S. Army M9A1 Field Protective Gas Mask
The U.S. Army M9 Field Protective Gas Mask used a 60mm M11 filter attached directly to the cheek. This design saw many years of use, and was copied by several other countries. Production began in 1951, but less than a year later the carrier was updated, and the designation was changed to M9A1. This example was made by Firestone in 1952.