Gomadic Portable AA Battery Pack designed for the HP iPAQ h3850 h3835 h3955 Series - 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 (HP iPAQ h3850 h3835 h3955 Series specific), TipExchange enabled (Yes) Integrated circuitry regulates output voltage specific to the HP iPAQ h3850 h3835 h3955 Series. 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. Safely engineered with reverse polarity protection, in the event batteries are accidentally put in incorrectly. This Gomadic Battery Pack is uniquely designed to work with both standard (e.g. alkaline) and/or rechargeable AA batteries.