Under Armour Mens UA ColdGear&reg; Infrared Grid &frac14; Zip Mock Gray Small Fitted: Next-to-skin without the squeeze. Dual-layer, textured-grid fabric traps heat with very little weight ColdGear Infrared technology uses a soft, thermo-conductive inner coating to absorb & retain your own body heat Contrast inner color & stitching 5.0 oz. Polyester/Elastane