Built with Under Armour's Lightweight ColdGear, the Under Armour UA Base 1.0 Crew for Boys is ideal for training when the temperatures are under 55F and the exertion levels are high. Moisture wicking and quick to dry, the Base 1.0 Crew has flat lock seams for all-day chafe-free comfort and ArmourBlockTechnology, reducing odor and keeping you feeling New throughout the day.