Features and Benefits: Quick-heat function reaches selected temperature 3X FASTER; One-touch LED controller with (3) heat settings; Up to (3) hours of run-time with REDLITHIUMT USB Battery Pack; Heating Zones: Chest & Upper Back; Washer and dryer safe; Powered by REDLITHIUM USB Battery Technology, Milwaukee Heated WORKSKIN Base Layers use carbon fiber heating elements to create and distribute heat to the chest and back. Combining a double lined polyester body and fleece lined arms, the midweight base layer provides a versatile layering piece for total body warmth. Raglan sleeves and seemless shoulders allow for improved range of motion and comfort while working.