Unique Gomadic Portable Rechargeable Battery Pack designed for the Samsung SGH-T139 - High Capacity Gomadic charger that fits in your pocket Integrated circuitry tailors output voltage and charging current to exact specification of the Samsung SGH-T139 (accurate to 0.1v). Specification: Internal Battery (7800mAh lithium polymer), Input port (microUSB), Output Port (Standard USB), Onboard Circuit Design (Samsung SGH-T139 Specific), Dimensions (2.75 X 3.25 X 0.75 inches), TipExchange enabled (Yes) Very easy to operate. Simply connect Samsung SGH-T139, press activation button on pack, and charging begins. Quick start guide included. Built with high capacity lithium polymer rechargeable battery technology (28 Wh / 7800 mAh) in a compact design. 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