Portable Emergency AA Battery Charger Extender suitable for the Apple iPhone 4S - with Gomadic Brand TipExchange Technology Built using the unique Gomadic TipExchange Technology that protects your investment by providing the ability to upgrade charging ports by simply swapping physical connectors. Integrated circuitry regulates output voltage specific to the Apple iPhone 4S. Advanced logic maximizes overall charger efficiency. Specification: Input Voltage (4 X AA Batteries), Cable length (6 inches), Dimensions (5.0 X 1.5 X 0.75 inches), Circuit Design (Apple iPhone 4S specific), TipExchange enabled (Yes) Safely engineered with reverse polarity protection, in the event batteries are accidentally put in incorrectly. Easy to operate. Simply insert batteries, toggle on/off switch and your Apple iPhone 4S will start to charge.