The Ergodyne Chill-Its 6630 High Performance Terry Cloth Skull Cap Is A Low-Profile Cap Featuring A Wide, Absorbent Terry Cloth Sweatband To Manage Perspiration Away From Your Eyes, Face And Glasses. The Hi-Cool Moisture Management Performance Fabric Is Stretchy To Fit Most Heads And Can Be Worn Under A Hard Hat Or On Its Own To Provide Sun-Blocking Protection. Low-Profile Design Fits Comfortably Under A Hard Hat Or Helmet And Is Great For Construction Workers, Landscaping, Roofing, Or Anybody Working In The Heat.,One Size Fits Most