Circle Pad Pro 3DS XL, available from March 2013
Nintendo during the Direct confirmation that from next March 22nd the Circle Pad Pro to 3DS XL. The accessory will add a second circle pad to the console, allowing you to use new control schemes in games that support the peripheral.
Note that the Circle Pad Pro will be compatible with Monster Hunter 3 Ultimate, Available for 3DS and 3DS XL starting March 22, 2013