Gomadic Unique Portable Rechargeable Battery Pack designed for the Panasonic HC-V770/HC-V777 - High Capacity charger that fits in your pocket Very easy to operate. Simply connect Panasonic HC-V770 / HC-V777, 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-V770 / HC-V777 (accurate to 0.1v). Specification: Internal Battery (7800mAh lithium polymer), Input port (microUSB), Output Port (Standard USB), Onboard Circuit Design (Panasonic HC-V770 / HC-V777 Specific), Dimensions (2.75 X 3.25 X 0.75 inches), TipExchange enabled (Yes) Continue to use your Panasonic HC-V770 / HC-V777 for hours OR recharge it on the go without being tethered to a wall outlet Internal circuit protects the Panasonic HC-V770 / HC-V777 from various power ailments including surges, overcharging and short circuiting. Advanced logic maximizes charger efficiency