For your consideration is this high quality and quite uncommon toy U.S. Military M1 helmet shell liner.
The real helmets of this style were used from the second world war through the Vietnam conflict.
The liners were sometimes worn without the steel cover as a stand-alone hard hat of sorts, mostly by rear units and MPs, as well as for ceremonial purposes.
This toy example is in a green/brown drab and has a patch bearing the acorn insignia of the 87th infantry division.
The condition is good for the vintage age of this piece, while the suspension is worn and the band is stiff and crispy.
Please see photos for more detail about this great old military toy collectible!