Califorinia Heat's 7V Vest begins warming your core within seconds using a compact, rechargeable 7V Li-Ion battery. The advanced heating technology (Finewire™) makes this vest the perfect heated base layer for hunting, fishing, and outdoor sports. Features: Constructed of rip stop Nylon & Lycra with spandex side panels Heating elements are located in panels on the chest and back Battery last 2-6 hours (depending on setting) Max Heat: 135° F Waterproof & windproof with breathable Hipora™ Lifetime warranty on Finewire™ heating elements and plugs Includes: Wall Charger 3500 mAh 7V rechargeable lithium-ion battery California Heat 7V Battery Heated Vest Liner