Adaptable for swimming, tubing, paddling, or just hanging around the beach, O’Neill’s short sleeve UPF 30+ Basic Skins sun shirt gives you a maximum value option for entry-level UV protection. 30+ UPF blocks 97 percent of the sun’s harmful rays (compare to 50+ UPF which blocks 98 percent). Slim fit fits closer than regular clothing to reduce drag in the water, but is more generous than a typical surfer’s rashguard. Two way stretch, 5 ounce polyester composite fabric.