Nintendo announced details on the retail release of "Circle Pad Pro" attachment today. The accessory, which adds a second circle pad and two extra shoulder buttons to the console, will cost 19.99 and will be in stores on February 7th...

Well, some stores.

Nintendo says that the Circle Pad Pro will be sold exclusive through Gamestop in the US.

The Circle Pad Pro will be compatible, but not required, with many of 2012's high-profile 3DS games, including Resident Evil: Revelations and Metal Gear Solid 3D: Snake Eater.