Gomadic Unique Portable Rechargeable Battery Pack designed for the Garmin nuvi 2589/2599 LMT - High Capacity charger that fits in your pocket Specification: Internal Battery (7800mAh lithium polymer), Input port (microUSB), Output Port (Standard USB), Onboard Circuit Design (Garmin nuvi 2589 / 2599 LMT Specific), Dimensions (2.75 X 3.25 X 0.75 inches), TipExchange enabled (Yes) Very easy to operate. Simply connect Garmin nuvi 2589 / 2599 LMT, 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 Garmin nuvi 2589 / 2599 LMT (accurate to 0.1v). Built using unique Gomadic TipExchange Technology that protects your investment by providing the ability to upgrade charging ports by simply swapping the physical connector. Designed with a front facing LED display that clearly display the current battery capacity at the touch of a button