Nike Trail AeroBill Trucker Hat Body: Dri-FIT 100% polyester. Back of front panel: 92% polyester/8% cotton. Back panels: 100% polyester. Underbill: 100% cotton. Imported AeroBill Technology provides lightweight breathability Dri-FIT Technology helps keep your head dry and comfortable Adjustable back closure for a personalized fit Reflective details are visible in low light