The Craft WARM Crew long sleeve is a lightweight base layer designed for intense aerobic activities on cold winter days. Hollow fibers are worked into a complex 3D knit with seamlessly integrated climate zones that correspond with different parts of your body. While the fibers and the spaces in between trap warm air for great insulation, the climate zone construction guarantees balanced temperature management so your body doesn't overheat. Seamless torso provides a close fit and is extremely elastic for full freedom of movement. Advanced moisture management wicks moisture away from your skin, while an antimicrobial treatment prevents odor from setting in.