M1 Steel helmet used onboard HMAS Kanimbla. These M1Steel 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. Interestingly, the Nato Stock Number (NSN) printed on the inside of the helmet liner indicates that this helmet was made for a Bulgarian contract, as evidenced by the NSN National code of 50 in the second group of numbers in the stock number. HMAS Kanimbla (LPA-51) was built for the United States Navy as USS Saginaw and was launched on 7 February 1970. Kanimbla was commissioned into the Royal Australian Navy in August 1994. Kanimbla was heavily involved in Operation Slipper conducting a variety of tasks such as patrol, mine recovery. During Operation Slipper, Kanimbla also conducted 27 compliant boardings and 23 non-compliant boardings in the Persian Gulf in 2001-2.Standard issue United States M1 pattern steel helmet, olive drab in colour with liner. On the inside of the liner '8415-50-753-5792' is printed in ink. The chin strap is made of webbing and has its metal claps attached for doing it it.8415-50-753-5792helmet, vietnam, protective helmet