Under Armour Men's Run Reflective CoolSwitch Calf Sleeves 80% Polyester/20% Spandex Imported AirVent insets on the inner arm deliver true breathability in a stretchy, durable, fast-drying fabric Reflective taping & UA logos increase visibility & safety on low-light runs Material wicks sweat & dries really fast 4-way stretch construction moves better in every direction