Flight Helmet, Gentex H-4, US Navy, US Marine Corps 1950's

Here is an Flight Helmet made by Gentex, type H-4, size Medium, used by pilots of the US Navy and US Marine Corps Aviation during the mid 1950's.  According to Andrea Salimbeti's website:

The {Gentex} H-4 was a further development of H-3. The rigid shell with reinforcing ridges, in different shape respect to the H-3 model, is constructed of a fiberglass cloth reinforced with epoxy resin. Also for this model a cloth inner helmet which incorporate the earphones was utilized. This was secured to the rigid shell by "pull the dot" snap fasteners on the cheek flaps and in some cases with additional straps attached to snap fastener in front and in the back of the rigid shell. The H-4 was equipped with a boom mounted microphone M-6A/UR to be used below 10.000 feet. Above this altitude an A-13A or A-14 oxygen mask were used. Black rubber goggles B-8 with modified straps to be attached to snaps placed on the sides of the helmet shell below the adjustment webbing were normally worn as well as normal goggles but in some case a USAF P series external visor were also installed.