The numbers 8 and 0 are heat temperature marks. A Navy aircraft carrier doesn't just launch aircraft — it projects power. Flag officers are only authorized to wear in the post-tour position described below. Dating M1 Helmet Liner -. History of U.
Dating M1 Helmet Liner -. Initially they were dyed olive drab number three which was technically a greenish khaki, but in practice was produced in varying shades from khaki to greenish khaki. It had a more comfortable helmet liner and an improved canvas chinstrap. By , new specifications had been adopted which changed how the M1 helmet was produced.