Rothco's Mesh Boonie Hat is made of a lightweight polyester with mesh ventilation about 3/4 of the boonie hat. The lightweight material and vent mesh has been designed to keep you cool, while protecting your head from the sun. Inspired by the classic military boonie the hat features branch loops, 3' brim, adjustable chin strap and sweatband. In addition, Rothco's Vented Mesh Boonie Hat is fully adjustable with an elastic cord and button lock, one size will fit most.