If you are familiar with R4  or any other flash cart, setting up the R4SDHC is the same.
R4 SDHC cartridge size is identical to that of the original R4DS cartridge.
The microSD card is inserted through the top of the cartridge and fits flush with the cartridge.

Features:
1. 2nd Generation Storage Device (no booting tool required)
2. Flush fitting Slot 1 Card
3. Uses microSD/microSDHC Memory Card (supports memory size up to 32GB), FAT16 or FAT32 File System
4. Supports any microSD/microSDHC Memory Card speed without lagging in game
5. Supports Clean ROM, drag and drop. Works on any OS
6. Built in NoPass
7. Automatically detect save type
8. Save directly to microSD Card, not to onboard chip
9. Supports Moonshell and other homebrew. Open I/O interface
10. User friendly skinnable interface. Touchscreen or button operation
11. Supports rumble pak and memory pak
12. Supports the WiFi game, DS Rumble Pak, DS Browser
13. Supports changes of the background of Operation Interface
14. Supports 4-scale-lightness adjustment (DS Lite only)
15. Supports Soft Reset
16. Supports Moonshell 1.6 Software Reset Function (press START keyback to the R4 Menu)