The American M17 gas-mask was used by the United States military during the 1960's up until the early 1990's, when it was replaced by the M40 gas-mask. The M17 was irregular for its time as it took two filters stored in the masks cheeks. This was designed to make the mask lighter and easier to breath through, however the filters could be hard to install and could not be changed during a gas attack. The M17A2 replaced the A1 version and included a drinking tube.
During the Cold War the two clones were made of this mask, the direct clone was the Czech-made OM10/M10M mask, and the Russian-made PBF, which incorporated similar features and design.