Standard issue United States M1 pattern steel helmet, olive drab in colou, stretch cotton cargo type net, with fibreglass liner. On the inside of a strap in the liner '8415-153-6671' is printed in black ink. This number would appear to be the "Federal Stock Number (FSN)" which was used 1949 to 1975 when ti was replaced by "National Stock Number (NSN)' by additional of 00 after the first 4 numbers. this would indicate that it was made in USA. The chin strap and liner are both complete and fully operable. These helmets were first issued in 1941 to the United States Armed Forces. They were adopted after the Korean War by the Australian Defence Force. In the 1990s they were replaced by the Kevlar based Personnel Armour System-Ground Troop (PASGT) type helmet. However, as evidenced by this helmet, some M1 Steel helmets were not replaced in-service by the PASGT helmet and survived into the early 21st Century. Used by Royal Australian Army in Vietnam in areas where mines were significnat, such as Long Hai's mountains (together with US flak jackets), and also by Royal Australain Navy.An example of an Australian Army issue M1 steel battle helmet complete with fibreglass liner. This helmet type was issued to Australian defence personnel during the Vietnam conflict. The inner line has a transfer on the front " Australian Military Forces" with rising sun badge. The steel outer has an olive green elastic cover (similiar to cargo net) to hold camouflage material. The M1 is two "one-size-fits-all" helmets: an outer shell made of metal and a hard hat-type liner that is nestled inside the shell and contains the suspension system that would be adjusted to fit the wearer's head. Helmet covers and netting would be applied by covering the steel shell with the extra material tucked inside the shell and secured by inserting the liner. The helmet is 7 inches in height, width is 9.5 inches and length is 11 inches. The weight of a World War II era M1 is approximately 2.85 pounds including the liner and chinstrap. (From Wikipepedia) the inner line has a transfer on the front " Australian Military Forces" with rising sun badge.steel helmet

Alloy badge featuring a rising sun and crownAustralian Commonwealth Military Forces