Unique Gomadic Portable Rechargeable Battery Pack designed for the GPS Spark Nano Tracker - High Capacity Gomadic charger that fits in your pocket Specification: Internal Battery (7800mAh lithium polymer), Input port (microUSB), Output Port (Standard USB), Onboard Circuit Design (GPS Spark Nano Tracker 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 GPS Spark Nano Tracker (accurate to 0.1v). Very easy to operate. Simply connect GPS Spark Nano Tracker, press activation button on pack, and charging begins. Quick start guide included. 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 Continue to use your GPS Spark Nano Tracker for hours OR recharge it on the go without being tethered to a wall outlet