Now built to keep you warmer and drier than ever in extreme cold, Under Armour's Base 3.0 traps heat with cozy grid fabric against the skin, while the smooth outer surface lets you layer with ease. Heavyweight UA Base 3.0 made from lightweight polyester and elastane aggressive warmth for extreme cold and a variety of activity levels. Fitted: Sits close to the skin for a streamlined fit without the squeeze of compression. Soft, brushed negative grid interior traps heat in tiny pockets, providing superior warmth without weighing you down. Smooth outer surface makes it easy to add layers. 4 way stretch fabrication allows greater mobility, maintains shape, and enhances dry time. Signature Moisture Transport System wicks sweat away from the body to keep you dry and comfortable. Quick dry fabrication keeps you light and comfortable. ArmourBlock anti odor technology prevents the growth of odor causing microbes to keep gear fresher longer. Winner waistband construction. Flatlock stitching prevents chafing. Ergonomic seam placement for mobility and comfort.