The Nike Ventilated Arm Band is compatible with most smartphones so you can take it with you when youre out exercising. It has a pocket with Velcro closure to securely store your phone, and then the arm strap easily adjusts for a personalised fit, which also gives you amazing breathability and comfort. The clear window gives you touch screen access and screen protection and the strap itself has reflective branding for added visibility in low light conditions. Pocket with velcro closure, adjustable & ventilated arm strap, clear window for touch screen access and screen protection. Composition: 45% nylon, 26% thermoplastic polyurethane,17%polyester,12%spandex. One size. Keep away from fire.