Type A-4 walking oxygen bottle, complete with AN-6022-1 (ex A-13) regulator for bomber aircrews. Dated 1944 on neck. All the A series oxygen masks can be plugged in with the quick disconnect system. Designed to walk away from an oxygen station to another and provide 3 to 8 minutes of oxygen at high altitude. Usually clipped on parachute's harness or flight jacket. Excellent condition. Oxygen mask isn't included.