The Sunday Afternoons Sport Hat protects you against the sun while enjoying outdoor activities. Crafted with lightweight, breathable nylon sun fabric with crown ventilation. UPF 50 sun protection. The Sport Hat features a crescent-shaped brim extending around the sides of the head and a overlaIRCHARing rear neck veil for full protection from the elements. The hat packs flat or rolls into a cone to make it easy to transport. Moisture wicking sweatband keeps your brow dry during aerobic activities. Rear sizing tape for a comfortable fit and a draw cord to keep the hat attached. Floatable brim keeps this hat on the water's surface if lost overboard. To fit your own personal style unique side 'brim-shapers' can be bent. Sizing (Head circumference): Medium: 21-23.5", Large: 23.5-24.5".