The M1C helmet was a variant of the U.S. Army's popular and iconic M1 helmet. Developed in World War II to replace the M2 helmet, it was issued to paratroopers. It was different from the M2 in various ways, most importantly its bails (chinstrap hinges). The M2 had fixed, spot welded "D" bales so named for their shape. It was found that when sat on or dropped, these bails would snap off. The solution was the implementation of the swivel bail, which could move around and so was less susceptible to breaking.