This affordable vest is perfect for the discreet seamless fit look. It’s made for all shapes and sizes and fits seamlessly on top of shirts and under jackets. The elastic waist band across the front ensures comfort and can be easily adjusted to fit your body type. With one large heating unit across the back this vest is sure to keep you toasty all day! Power connector with USB port that is compatible with UL certified power banks with output of 5-6V (Vdc) / 2.2A (Max).