Powerful Lithium Polymer Rechargeable Gomadic Brand Battery Pack High Capacity Portable Charger Compatible with Garmin EDGE 810 with upgradeable TipExchange Technology Very easy to operate. Simply connect Garmin EDGE 810, press activation button on pack, and charging begins. Quick start guide included. Specification: Internal Battery (7800mAh lithium polymer), Input port (microUSB), Output Port (Standard USB), Onboard Circuit Design (Garmin EDGE 810 Specific), Dimensions (2.75 X 3.25 X 0.75 inches), TipExchange enabled (Yes) Integrated circuitry tailors output voltage and charging current to exact specification of the Garmin EDGE 810 (accurate to 0.1v). Internal circuit protects the Garmin EDGE 810 from various power ailments including surges, overcharging and short circuiting. Advanced logic maximizes charger efficiency Built using unique Gomadic TipExchange Technology that protects your investment by providing the ability to upgrade charging ports by simply swapping the physical connector.