The NIKE AeroBill Featherlight Cap is made with sweat-wicking fabric and perforated insets to help keep you cool and dry. An adjustable strap in back lets you customize the fit. Body/Bill: 100% Polyester; Sweatband: 91% Recycled Polyester/9% Spandex Imported Dri-FIT Technology helps keep you dry and comfortable Mesh panels and interior perforated panel for breathability Hook-and-loop back closure with reflective pull tab for an adjustable fit