TKO Sweat-Wicking Sports Arm Sleeve for iPhone 6 and other Smartphones EXTRA LARGE SWEAT WICKING AND BREATHABLE MATERIAL for use in sports and recreation. Fits iPhone 6 and other Smartphone models. PVC WINDOW allows you to view and control your Smartphone while exercising. SMALL / MEDIUM 9-13" circumference LARGE 12-17" circumference XLARGE 16-19" circumference