Gomadic High Capacity Rechargeable External Battery Pack suitable for the Panasonic HC-W850 / W850 Specification: Internal Battery (7800mAh lithium polymer), Input port (microUSB), Output Port (Standard USB), Onboard Circuit Design (Panasonic HC-W850 / W850 Specific), Dimensions (2.75 X 3.25 X 0.75 inches), TipExchange enabled (Yes) Very easy to operate. Simply connect Panasonic HC-W850 / W850, press activation button on pack, and charging begins. Quick start guide included. Integrated circuitry tailors output voltage and charging current to exact specification of the Panasonic HC-W850 / W850 (accurate to 0.1v). Internal circuit protects the Panasonic HC-W850 / W850 from various power ailments including surges, overcharging and short circuiting. Advanced logic maximizes charger efficiency Charging kit includes: Rechargeable Lithium Battery Pack, USB input/output cable, Panasonic HC-W850 / W850 Charging Connection, and Battery Pack input connection.