Description of Royal Robbins Extreme Expedition S/S Shirt - Women's This wrinkle resistant, lightweight fabric with UPF 40+, incorporates special fibers that channel moisture away from the body to help keep wearers dry. Grid-like construction makes this fabric highly durable and resistant to abrasions, punctures and tears. Features: Coolmax Extreme Expedition Ripstop 2.9oz, 100% Coolmax polyester UPF 40+ Wrinkle resistant Dri X-treme mesh lined vented back and collar band Zippered venting at back Strider at center back yoke