Under Armour Men's HeatGear Armour Short Sleeve Compression Shirt 84% Polyester, 16% Elastane Imported HeatGear fabric, with all the benefits of UA Compression, comfortable enough to be worn all day Stretch-mesh underarm panels deliver strategic ventilation UPF 30+ protects your skin from the sun's harmful rays 4-way stretch construction moves better in every direction Material wicks sweat & dries really fast