Mobile Warming Women's Classic Vest - 3W/Black The Windshark 4-way stretch high breathable, waterproof fabric provides additional flexibility needed in active outdoor sports Features three heating panels lined with steel alloy fiber elements, Optimum placement with two panels on the chest and one on the back provide quick warm-up and even distribution of heat where needed most Includes one 7.4V 2.2Ah rechargeable lithium-ion battery and charger Battery features built-in 4-level thermo-regulating controls Provides up to 10 hours of comfortable warmth while enjoying favorite outdoor activities, Reaches a max. surface temperature of 135F at full power