The Under Armour Alter Ego Compression Shortsleeve is an ultra-tight, second-skin fit, which delivers a locked-in feel for optimum muscle performance. The HeatGear® fabric that makes up the top, with the benfits of UA Compression, makes this top comfortable enough to be worn all day. The 4-way stretch fabric allows you to move freely and naturally, whilst still maintaining its shape. Under Armour's signature Moisture Transport System wicks away sweat, keeping you cool and dry, whilst Anti-Odour technology prevents the sweat from forming odour causing microbes. UPF 30+ protects your skin from the sun's harmful rays. The smooth flatlock seams eliminate the chance of irritation through chafing, providing you with maximum comfort.