This is a commercial/medical version of the ultra-rare USAAF A-7 nasal oxygen mask. Introduced in 1939, the A-7 featured a green rubber facepiece that only covered the nose. Integral oxygen feed channels pass from the nosepiece around either side of the mouth and join under the chin just above a metal valve. A thin rubber rebreather (Bladder) bag sits beneath this and oxygen is supplied via a length of thin rubber tubing. This example appears to be a commercial pattern and has an identical facepiece but lacks the valve. This is in very good flexible condition as is the oxygen tube and simple rubber strap system - all with remains of the chalk used to preserve the rubber when packed. Sadly the rebreather bag has perished and is rock hard. I believe reproduction bags are available online - they are the same as those used on the A-8 series masks. Not quite a true A-7 but probably as close as you are likely to find and would make an excellent display piece. Stock code O7211.