This is an original early-WWII Westinghouse manufactured M1 helmet liner. It exhibits a relatively uncommon flaw - "bubbling". High pressure helmet liners like this one consist of resin-impregnated duck cloth which was cut to size and then overlapped into the rough shape of a helmet liner. These overlapping materials were then compressed between male and female steel molds - hence the name "high pressure". When released, the helmet liner was given time to cure before undergoing further processing. We're not sure if the bubbling occurs due to a lack of resin in a particular layer, the press having issues with the liner's curved surface, or if insufficient time was given to cure the liner, but it is certainly unusual! The liner's exterior showcases its original olive drab factory finish. The non-painted steel A-washers date the liner's production from late-1942 to mid-1943. The khaki suspension is torn in one spot and is missing its drawstring. It comes complete with its original double-wire headband and neckband. The headband's leather has unfortunately deteriorated. This liner would pair quite nicely with a fixed loop M1 helmet shell in equally rough condition. The liner has also been tested in a shell and the bubbling has no impact whatsoever on its ability to fit inside a helmet.