Under Armour ColdGear Compression Mock Long Sleeve Mens T Shirts. Comfortable workout gear is at your fingertips with the Under Armour ColdGear Compression Mock Long Sleeve t shirt. A dual layer of fabric helps provide you with a warm, comfortable wear thanks to ColdGear technology. Moisture Transport System works to wick away moisture as you start to perspire in your workout. Anti-odor technology has been built into the fabric to keep you feeling fresh. The flat seams allow for a chafe-free fit. A mock neck finishes off the compression fit of this shirt.