Under Armour Base 2.0 Crew - Junior Boy's: This isn't your grandpa's long underwear. The unique negative grid traps monster warmth without adding weight and it's smooth on the outside to let you layer. UA Base 2.0 is the most versatile of the UA Base thermals, built for basically anything you do outside. Running to hunting, the hill or the woods, this guy has got you covered. THE FUNDAMENTALS FITTED: Sits close to the skin for a streamlined fit without the squeeze of compression. UA Base 2.0 is highly versatile mid-weight protection for colder conditions and a variety of activity levels Soft, brushed negative grid interior traps hot air, providing superior warmth 4-Way Stretch fabrication allows greater mobility and maintains shape Signature Moisture Transport System wicks sweat away from the body Quick-dry fabrication keeps you light and comfortable Anti-Odor technology prevents the growth of odor causing microbes Raglan sleeve construction and flatlock stitching allow a full range of motion without chafing 4.7 oz. Polyester/Elastane