Under Armour Base Layer 2.0 Quarter Zip is fitted: Next-to-skin without the squeeze. UA Base 2.0 is built for cold conditions and moderate activity levels. This has a soft, brushed negative grid interior that traps hot air, providing superior warmth. It is made of a 4-way stretch fabrication that allows greater mobility in any direction. Moisture Transport System wicks sweat away from the body and the Anti-Odor technology prevents the growth of odor causing microbes.