Students don MBU-12 oxygen masks before using the parachute hang at the station's Aviation Physiology Training Unit - NARA & DVIDS Public Domain Archive Public Domain Search
MBU-12/P Oxygen Mask & Parts • Gibson & Barnes
Mask, Oxygen, Type MBU-12/P, United States Air Force | National Air and Space Museum
USAF Major HGU-55P / MBU-12P - early 90's - FLYING HELMETS AND ACCESSORIES - U.S. Militaria Forum