Under Armour Men's UA ColdGear Infrared Heartbeat188; Zip ColdGear Infrared technology uses a soft, thermo-conductive inner coating to absorb & retain your own body heat Soft anti-pick, anti-pill fabric has a cleaner, snag-free finish 4-way stretch fabrication allows greater mobility in any direction Moisture Transport System wicks sweat away from the body Anti-odor technology prevents the growth of odor causing microbes