The main purpose of arm protection sleeves is to provide a barrier between your skin and the sun. The sleeve covers both arms so that no exposed skin is exposed at all. Arm protection sleeves can be made of many different materials, including nylon and polyester. Some are made from special fabrics that reflect sunlight and ultraviolet rays away from your skin instead of absorbing them in like other fabrics do. You can wear arm protection sleeves on their own or underneath other clothing items such as long-sleeved shirts or sweaters if you have sensitive skin that burns easily when exposed to sunlight.