AA Battery Portable Charger Power Pack Power Supply / UPS for the Raspberry Pi Model B / Model B+ / Model A+ Motherboard Output voltage a perfect match for both Model B and Model B+ Raspberry Pi. MicroUSB interface connector Built using the unique Gomadic TipExchange Technology that protects your investment by providing the ability to upgrade charging ports by simply swapping physical connectors. Specification: Input Voltage (4 X AA Batteries), Cable length (6 inches), Dimensions (2.5 X 2.5 X 0.75 inches), Circuit Design (Raspberry Pi specific), TipExchange enabled (Yes) Safely engineered with reverse polarity protection, in the event batteries are accidentally put in incorrectly. This Gomadic Battery Pack can be reused forever by simply inserting fresh batteries, providing instant power on demand.