Gomadic Portable AA Battery Pack designed for the HTC Desire S - Powered by 4 X AA Batteries to provide Emergency charge. Built using TipExchange Technology Specification: Input Voltage (4 X AA Batteries), Cable length (6 inches), Dimensions (5.0 X 1.5 X 0.75 inches), Circuit Design (HTC Desire S specific), TipExchange enabled (Yes) Integrated circuitry regulates output voltage specific to the HTC Desire S. Advanced logic maximizes overall charger efficiency. Built using the unique Gomadic TipExchange Technology that protects your investment by providing the ability to upgrade charging ports by simply swapping physical connectors. Easy to operate. Simply insert batteries, toggle on/off switch and your HTC Desire S will start to charge. This Gomadic Battery Pack is uniquely designed to work with both standard (e.g. alkaline) and/or rechargeable AA batteries.