Powerful Lithium Polymer Rechargeable Gomadic Brand Battery Pack High Capacity Portable Charger Compatible with Garmin Nuvi 50 50LM with upgradeable TipExchange Technology Integrated circuitry tailors output voltage and charging current to exact specification of the Garmin Nuvi 50 50LM (accurate to 0.1v). Specification: Internal Battery (7800mAh lithium polymer), Input port (microUSB), Output Port (Standard USB), Onboard Circuit Design (Garmin Nuvi 50 50LM Specific), Dimensions (2.75 X 3.25 X 0.75 inches), TipExchange enabled (Yes) Very easy to operate. Simply connect Garmin Nuvi 50 50LM, press activation button on pack, and charging begins. Quick start guide included. Designed with a front facing LED display that clearly display the current battery capacity at the touch of a button Continue to use your Garmin Nuvi 50 50LM for hours OR recharge it on the go without being tethered to a wall outlet