The US Army HBT Cap is made of herringbone twill material. The size of the hat is XL / Extra Large. More sizes coming soon.
Adopted in 1941, the herringbone twill work cap was to be worn with the one-piece HBT coveralls. By 1946, the cap, officially known as CAP, HERRINGBONE TWILL, was designated for specialty troops only. Henri-Paul Ejames’ book, Government Issue, lists the cap as being issued specifically to armored troops, but photographs show it being worn by ordnance, infantry troops, and aircraft ground crew, despite having their own USAAF issued HBT baseball cap.