This is a 1950s vintage F-9F Panther oxygen regulator. It was removed from a scrapped jet fighter. Used very good condition. Original data plate is Bureau of Aeronautics marked and is a composite diluter demand oxygen regulator. Measures 5 ½ inches in diameter. Has a cylinder pressure gauge, safety pressure switch, ON/Off oxygen supply switch and a flow indicator. If you love old Navy jet stuff, this is for you. $19.95