H-1 Bail Out oxygen bottle, complete with cover, tube and mouth piece, for fighter pilots and bomber aircrews. Dated March 1943 on neck. Designed to provide 10 minutes of oxygen at high altitude in case of failure of the aircraft main oxygen system or to bail out if the airplane couldn't be taken to a lower altitude before abandoning it. Usually strapped on the thigh or parachute's harness as can be seen on this period pic of 8th Air Force Ace Francis Gabreski. Mint condition.