100% Polyester Baselayer – Smooth and ultra-soft fabric provides extreme comfort with very little weight without restriction Button closure Lightweight, moisture-wicking nylon keeps you cool and dry. UPF 50+ rating provides excellent protection against harmful ultraviolet rays.If you enjoy outdoor activities, this is the best one for you. Turn down collar, Button down front closure. Button closure. Mesh-lined vents at center back to keep the breeze flowing in and the heat flowing out to help all-day cooling in the sun. Roll-Up Sleeve with tab holders – exterior tabs at upper arm to convert to a short sleeve.