SDXC Memory Cards (Through an update, SDXC cards up to 128GB are now compatible to the 3DS provided it is somehow formatted to fat32 which it generally isn't out of the box) ...

How to Format a Scan Disc Memory Card. Memory cards are small, removable media cards most commonly used inside of cameras and smart phones. They hold images, songs and even small programs.

How do I reset/format/delete the data for Face Raiders and other 3DS software? From the main menu, choose System Settings > Data Management > Nintendo 3DS > Extra Data.

The Extended File Allocation Format system also provides support for files larger than 4GB. Formatting your USB memory stick allows you to clear the device and enable the NTFS or exFAT file structure.