Specially engineered HEATR® fabric integrated into these base layers provide maximum warmth with less bulk by expanding to generate additional heat when in contact with your skin. Anti-microbial technology assists in destroying and inhibiting the growth of bacteria while simultaneously cutting down odor. Soft, stretchable fabric with flat seams for all-day comfort. Long sleeve shirt features ¼ zipper at neck for added venting comfort. The pants are body-mapped with thinner spandex in the gusset and calf area for ventilation and flexibility. For temps from -20º to 50º F. 70% Polyester, 27% HEATR®, 3% Spandex. Black. Sizes XS-XL. Made in America