Vietnam War US Army Original M1 Infantry Helmet P55 Liner 503rd MP Bat Original US WWII Korean War Era Paratrooper M1 Helmet Liner by CAPAC Cold War Soviet Memorabilia for Sale M51 Otan Helmet with Green Hood Cover. ORIGINAL POST WWII KOREAN WAR US ARMY M1 HELMET LINER US 45 #4747518274 Original French M51 Steel Helmet And Liner Dated 1953 ALGERIAN INDO. Original French, Late Pattern, M51 Helmet Liner Made of a durable ABS plastic in 1970. Notice the similarities between this M51 liner and the US M1 liner. The French also changed the design by negating the nape strap around the same time period as the US M1 did. This is an individual, one of a kind listing = There is only ONE and this is the one you will get!