The REDLITHIUM™ USB Heated Base Layer is powered by REDLITHIUM™ USB Battery Technology with carbon fibre heating elements to create and distribute heat to the chest and back. A one-touch LED controller allows you to select from two heat settings, delivering ideal heat for any environment. The Quick-Heat function allows you to feel heat 3X faster in the chest and upper back heating zones. Combining a double-lined polyester body and fleece-lined arms, the REDLITHIUM™ USB Heated Base Layer provides a versatile layering piece for total body warmth. This battery heated shirt features raglan sleeves and seamless shoulders for an improved range of motion and comfort while working.