HELIKON-TEX GI Boonie Hat Polish Woodland Head circumference (recommended): S (55-56cm), M (57-58cm), L (59-60cm), XL (61-62cm) 4 air vents on both sides of hat Wide reinforced brim. Adjustable chin strap Comfortable and lightweight. Tough and hard wearing Material: Polycotton Ripstop (60% Cotton, 40% Polyester)