Under Armour Men's Lightest Warmest ColdGear Infrared 1/4 Zip Vest, Black /Steel, X-Large

You'll never want to take this off-it feels like your T-shirt, only warmer. That's because the ColdGear Infrared technology holds just the right amount of extra heat without adding any weight or bulk. ColdGear Infrared technology uses a soft, thermo-conductive inner coating to absorb & retain your own body heat. Insanely soft, smooth fabric for total comfort, all day long. 4-way stretch fabrication allows greater mobility in any direction. Moisture Transport System wicks sweat & dries fast. Smooth, chafe-free flatlock seam construction.