Powerful Lithium Polymer Rechargeable Gomadic Brand Battery Pack High Capacity Portable Charger Compatible with Garmin EDGE 500 with upgradeable TipExchange Technology Very easy to operate. Simply connect Garmin EDGE 500, 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 500 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 500 (accurate to 0.1v). Continue to use your Garmin EDGE 500 for hours OR recharge it on the go without being tethered to a wall outlet Elegant, compact design is approximately the size of a standard deck of playing cards. Rugged exterior is built to last and backed by Gomadic Lifetime Warranty