Tested during the 1950 evaluation process, the P-1A was, with a notable delay, delivered and handed over to the Swiss AF by late summer 1953.
The P-1A was constructed of pressure and heat molded laminated cotton saturated with phenolic-resin.
It used an internal head suspension sling similar to that used in Army infantry helmet liners and tanker crew helmets, consisting of a leather and cotton sling that could be adjusted through the use of laces at the rear of the shell.
The helmet was deemed to be too heavy and with a tendency to heat build-up. By consequence this type of helmet was dismissed from the evaluation process.