This Heated Puffer Vest powered by M12™ REDLITHIUM™ Batteries, is a lightweight and durable vest featuring an advanced heat technology system utilizing carbon fiber heating elements.Quick-Heat functionality, distributes heat 3X faster than market competitors to the chest and back.The compressible, wind and water-resistant design can be used as an outer shell or mid-layer vest depending on the situation. Milwaukee - Heated Bodywarmer - Black - 2020ppe Size S