This is an original early-WWII U.S. Army Air Force Type A-9 summer flying helmet. These were the predecessors to the AN-H-15. This particular example bares a 1942-dated contract code, and is a size medium. The fleece-lined chinstrap has unfortunately come detached from one side of the helmet due to failed stitching. Nonetheless, it still displays quite nicely on a standard display head (not included).