Highly Elastic and Anti-Slip - Made with 90% Nylon and 10% Spandex fabric,the arm sleeves are stretchy to fit all arm perfectly, tightly-fit,anti-slip but no pressing feel.Extremely Elastic Material Cooling Arm Sleeves - Cooler than Bare Skin. Perfect for All Outdoor Indoor Activities even Work-space. UV-R, UV-A, UV-B BLOCK 99.8%High Performance Fabric -Fast Sweat Kick-away Fast Dry . Keep you warm in cold temperatures, keep you cool in hotter temperaturesThe elastic material fits to the arm curve, helping the arm to release the pressure better