Gomadic Powerful Lithium Polymer Rechargeable Brand Battery Pack High Capacity Portable Charger Compatible with Garmin nuvi 2539/2559 LMT with upgradeable TipExchange Technology Very easy to operate. Simply connect Garmin nuvi 2539 / 2559 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 2539 / 2559 LMT (accurate to 0.1v). Specification: Internal Battery (7800mAh lithium polymer), Input port (microUSB), Output Port (Standard USB), Onboard Circuit Design (Garmin nuvi 2539 / 2559 LMT Specific), Dimensions (2.75 X 3.25 X 0.75 inches), TipExchange enabled (Yes) Built with high capacity lithium polymer rechargeable battery technology (28 Wh / 7800 mAh) in a compact design. Charging kit includes: Rechargeable Lithium Battery Pack, USB input/output cable, Garmin nuvi 2539 / 2559 LMT Charging Connection, and Battery Pack input connection.