The Under Armour Women's ColdGear Reactor Vest is a top-rated sleeveless lightweight thermal packable activewear vest designed for cold weather conditions. It features UA ColdGear Reactor intelligent insulation that adapts to your activity level, providing the right amount of warmth and breathability. The vest is made from a combination of polyester and elastane, offering a comfortable and stretchy fit. It also has a quilted design and a stand-up collar for added style and protection. With its innovative technology and high-quality construction, this vest is a popular choice among athletes and outdoor enthusiasts.