Under Armour Men's CoolSwitch Short Sleeve Compression Shirt 92% Polyester/8% Elastane Imported UA CoolSwitch uses an exclusive coating on the inside that pulls heat away from your skin, so you actually feel cooler Mesh HeatGear fabric, with all the benefits of UA Compression, delivers total ventilation 4-way stretch construction moves better in every direction Material wicks sweat & dries really fast Anti-odor technology prevents the growth of odor-causing microbes