Under Armour HeatGear® Compression Shirts are an ultra-tight compression, second skin fit. HeatGear® fabric with the benefits of Under Armour Compression are comfortable enough to be worn all day. The stretch-mesh underarm panels deliver strategic ventilation and UPF 30+ protects your skin from the sun?s harmful rays. 4-way stretch fabrication allows greater mobility in any direction and anti-odor technology prevents the growth of odor causing microbes. The Moisture Transport Systems wicks away sweat and dries fast.