This pressure helmet is a transparent bubble made for and worn by James Irwin, Lunar Module Module pilot for the Apollo 15 mission in July, 1971.
The Apollo pressure helmet was a transparent bubble designed to attach to the spacesuit neck ring. It was constructed of a polycarbonate shell with a red anodized aluminum neck ring, a feed port, a vent pad and duct assembly attached to the rear and a valsalva device attached to the inner ring. The valsalva device was installed so that the astronaut could "blow" his nose to prevent his ears from "popping" during the rapid ascent of launch.
There were two configurations of these pressure bubbles used on Apollo suits which were not interchangable. The style used during the Apollo missions 7 through 10 was of anodized blue aluminum, while those used from Apollo 11 through the end of the program were of anodized red aluminum.
Transferred to the National Air and Space Museum from NASA in 1974.