The Circle Pad Pro attachment needs its own AAA battery, but don't think you'll need to shell out on new ones every time you fancy a game of Resident Evil Revelations.

According to one eager Japanese early adopter, the device's instructions claim it can last for up to 480 hours on a single AAA battery. Good job too, as the battery itself is kept in a compartment held shut by a screw.

The 3DS Circle Pad Pro reaches Europe on 27th January 2012.