The M-1 helmet has a protective rim that covers the edge of the helmet shell. The rim started and
ended at the front of the helmet. A seam was created where the start and endind pieces meet. This
is known as the "front seam", a unique characteristic of WWII helmets.
The M-1 helmet could be outfitted with a fixed or swivel bail. The erly war examples (1941) came
equipped with the fixed bail. It was soon realized that this was a flawed design since too much
stress was applied to a rigid structure. The swivel bail solved the breakage problems by being able
to move with the applied forces instead of opposing them.
The swivel bail design remained in use for the entire life of the M-1 helmet.