This pressure helmet was worn by numerous astronauts during training sessions prior to the Apollo missions of the 1960s.
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.
There were two configurations used on Apollo suits, which were not interchangable. The earlier configuration was anodized blue, and the later configuration anodized red.
Transferred from NASA in 1973