Two new accessories for the Raspberry Pi are providing even possibilities for the already popular single-board computer. The Gumstix Raspberry Pi Battery Pack, as its name implies, allows a Raspberry Pi to be run off two AA batteries, for example, while the MKR Module makes the board's GPIO ports safer to use.
https://www.notebookcheck.net/Raspberry-Pi-New-accessories-bring-battery-operation-or-more-security-to-the-developer-board.453214.0.html