The K-1 full pressure helmet was designed and developed at the US Wright Aero Medical Laboratory and was to be worn with partial pressure suits.
The first K-1 version had a two-pieces split outer hard shell and a faceplate made by two flat pieces of tempered glass held in place by a hard rubber frame. The plastic half shells were fitted over the rubberized nylon hood by means of a curved metal fairing.
A late “improved” (pictured) version featured a single piece moulded Plexiglas faceplate, thus increasing visibility, and a single piece glass fibres outer shell.
The helmet design had also some shortcomings: at high altitudes with great sky-cockpit light intensity variation, the visor could impair vision, making it difficult to read instruments. Another problem was the severely hampered wearer’s head mobility, thus significantly reducing his field of vision.