VIETNAM Era USAF Polyester Wool GARRISON CAP Size 6 7/8 Serge Blue The Vietnam Era USAF Garrison Cap in Serge Blue is an original period item from the Vietnam War era. This collectible militaria piece is made of polyester wool and showcases the military theme of the time. With a size of 6 7/8, this cap was worn by members of the USAF during the conflict in Vietnam. It serves as a unique and historically significant piece for collectors interested in the artifacts of this specific era.