66D1612612-2 / USAF Part No. Sierra MBU-5/P Quick Don Oxygen Mask (complete with CRU-60/P connector). There's also a blue plastic storage covering with an elastic band that fits over the breathing end of the mask. There is a tag on the bag handle that reads "Due 7 June 1968". Pilot's flight checklist notebook.
Condition issues: The inner foam of the helmet is disintegrating and a couple of the brown liner pieces are loose (including the main one on top). The foam in the headsets is quite disintegrated or missing entirely on one ear or the other.These would need cleaning and replacement, Stored in a smoke-free environment.