The Under Armour Women's ColdGear Reactor Vest is a top-selling sleeveless hooded reversible thermal activewear vest. Made with ColdGear Reactor technology, this vest adapts to your body's temperature to keep you warm without overheating. The sleeveless design allows for unrestricted movement, while the hood provides added protection against the cold. Whether you're hitting the gym or going for a run, this vest will keep you comfortable and stylish.