Under Armour Men's CoolSwitch Sleeveless Compression Shirt 92% Polyester/8% Elastane Imported UA CoolSwitch uses an exclusive coating on the inside that pulls heat away from your skin, making you actually feel cool & able to perform longer Mesh HeatGear fabric, with all the benefits of UA Compression, delivers total ventilation 4-way stretch fabrication allows greater mobility in any direction Material wicks sweat & dries really fast Anti-odor technology prevents the growth of odor-causing microbes