100% Polyester Imported Pull On closure Machine Wash Durable stretch knit, one-piece construction delivers all-day comfort, flexibility & warmth Interior fleece lining adds soft, next-to-skin warmth & comfort The technology behind Under Armour's diverse product assortment for men, women and youth is complex, but the program for reaping the benefits is simple: wear HeatGear when it's hot, ColdGear when it's cold, and AllSeasonGear between the extremes.