Rothco's Mesh Boonie hat is fully adjustable, with an elastic cord and button lock that adjusts the circumference (up to 24 inches) of the hat for a custom fit. The boonie is made of lightweight polyester with mesh ventilation that covers about 3/4 of the crown aiding in ventilation around your head, keeping you cool and dry, while the 3 inch brim protects your head and face from the sun during outdoor activities. Inspired by the classic military boonie, the Rothco mesh boonie hat features branch loops, a chin strap with button lock, and a sweatband.