UA Base 2.0 Active Baselayer is lightweight, flexible & breathable for high activity in cool conditions; UA Scent Control Technology to keep you undetected in all pursuits; Soft, brushed grid interior traps air, managing your body's microclimate to keep you warm & comfortable; Material wicks sweat & dries really fast; 4-way stretch material moves better in every direction; 81% Polyester/19% Elastarell