The P-38 steel can opener, developed in 1942, is a small can opener that was issued in the canned field rations of the United States Armed Forces from World War II to the 1980s. Known as the "John Wayne"ÂÂ style can opener, the hand can opener is a small but useful tool that has been used by generations of military personnel and is a great addition to anyone's survival kit! The keychain/dog tag chain hole allows the military can opener to be readily available at any time by attaching to your keys or dog tag chain.