M-1C Airborne Helmet / Paratrooper Helmet Liner Chin Cup. This is the standard web chin cup that buckles into the "A Straps" on the M-1C Airborne helmet liner. These are in unissued condition and are U.S. stamped (this shows manufacture between 1955 and 1965) There are four grommets on each side allowing for attachment / adjustment with the helmet liner.