Stay warmer and drier with less bulk in these comfortable, lightweight base layers. Proprietary HeartR® fabric technology is integrated throughout the garments, creating additional heat by expanding and heating up when it comes into contact with your skin. Heating performance is part of the fabric and will not wash out. The anti-bacterial and advanced wicking synthetic fabric is soft and stretchable for all-day wear. Long sleeve crew neck top and bottoms both feature flat seams for added comfort, with the pants also using a slightly thinner fabric layer below the calf and gusset area for enhanced breathability and mobility. An ideal layer for temps from 0º to 75º F. 70% Polyester, 27% HEATR®, 3% Spandex. Black. Unisex Sizes XS-XL. Made in America