PERFECT DESIGN- There are anti-slip particles inside the armband to ensure that the armband will not slip off during exercise; the armband surface is reflective to make you feel more secure at night; the phone armband has 3 openings and a headphone jack to carry mobile phones, MP3, MP4, keys, door cards, room cards, cash and other small items necessary supplies.COMFORTABLE AND BREATHABLE - Made of high-stretch fabric of 92% polyester and 8% spandex, moisture-wicking, quick-drying, flexible armbands are lightweight and easy to fit on your hands, so you don't feel it's there when you're exercising; Other phone armbands are bulky, uncomfortable, and rub against your skin during exercise. Our soft and comfortable material holds your phone securely without squeezing, irritating and distracting.SIZE RECOMMENDATION - Please measure your bicep circumference (unflexed) to ensure a fit. Small: 7'' - 9.1''; Medium: 9.2" - 10.6"; Large: 10.7" - 13"; Extra Large: 13.1''-17''.Made for - The sleek design makes it the perfect phone armband for an active lifestyle. If you enjoy working out, running, biking, lifting weights, walking the dog, hiking or doing outdoor activities in the kitchen, this armband is perfect for you..