Gomadic Portable AA Battery Pack designed for the Garmin Nuvi 850 - 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 (Garmin Nuvi 850 specific), TipExchange enabled (Yes) 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 Garmin Nuvi 850. Advanced logic maximizes overall charger efficiency. This Gomadic Battery Pack can be reused forever by simply inserting fresh batteries, providing instant power on demand. Easy to operate. Simply insert batteries, toggle on/off switch and your Garmin Nuvi 850 will start to charge.