First produced in 1951, the post WWII design M1 Helmet was standard issue for U.S. Soldiers and Marines throughout the Vietnam War.1 Made from Hadfield Manganese steel, it featured rolled edging and was coated in an olive green paint that contained silica sand. The helmet was equipped with two hinged loops for attaching a two-piece webbing chinstrap, which fastened with a ball-hook closure. The Parachutist's chinstrap differed slightly from the Infantry version, having snap fasteners to attach it to the helmet liner. Troops in Vietnam often kept the strap out of the way by fastening it across the back of the helmet or by tucking it into the helmet band.
Worn with the liner (Infantry or Parachutist) the M1 helmet weighed approximately 3.16 pounds and protected the wearer from shrapnel and glancing bullet blows, but would not stop a direct hit.
1. Reynosa, Post-World War II M-1 Helmets, pp 31