this is an interesting helmet.  I believe it is some sort of plastic with a leather brim.  On the inside you can see in the last couple of photos that it has been cut  in a pie shape on both sides and front and back..  I do not know if this was factory or someone just making the helmet larger.  The leather brim is sewn onto helmet with what I think is leather stripping around helmet and side to side and back to front.  Around a size 7.  Thanks.