The Sunday Afternoons Sprinter Cap is perfect for all outdoor adventures and lets you stay active while protecting you from the elements. Great for running, tennis, golf, and everyday casual wear. Made with 100% polyester ultra breathable mesh fabric, the Sprinter Cap is designed for sun protection on the go and wicks away moisture while providing UPF 50+ protection against harmful UV rays. Rear adjustable hook & loop strap allows for custom fit. 8" extra wide brim shades your face from the sun. 3.25" long cap brim shields the back of your neck and protects ears from the sun's rays. Integrated wicking sweatband liner keeps your head cool and dry. The cap has an open back to accommodate a pony tail. Packs easily for travel. Sizing (Head circumference): Medium: 21.5-23", Large: 22.75-24".