Boonie Hats were first worn by U.S. Army Green Berets in the Vietnam War. The style caught on and the hats are still worn today by servicemen of all branches in place of the patrol cap.
The hats are similar to bucket hats but have a slightly stiffer brim and branch loops around the base of the hat. These loops were made to hold foliage and further camouflage U.S. Army and other military soldiers while in the field or on patrol.
The hats come in two sizes that fit the vast majority of customers:
Small - Medium = 7 ¼ inches
Large = 7 ½ inches