My cousin brought them back from his trip. It lets you load mutiple games as well as movie/music files into one card(using any MicroSD). I love it. It turned my DS Lite into a mini harddrive that plays games, movies and stores files. I have an extra one for sale. $59 shipped to 48 states.
Email me at phatmitzu@msn.com.

R4DS
-2nd generation storage device (no booting tool required)
-Flush fitting slot 1 card
-Uses MicroSD card, FAT16 or 32
-Supports any MicroSD card speed with no lag in game
-Supports Clean ROM, drag and drop. Works on any OS
-Built in NoPass
-Automatically detect save type
-Save directly to MicroSD card, not to onboard chip
-Supports Moonshell and other homebrew. Open I/O interface
-User friendly skinnable interface. Touchscreen or button operation
-Supports rumble pak and memory pak
-Supports the WiFi game, DS Rumble Pak, DS Browser
-Supports changes of the background of Operation Interface
- Support Skin DIY by setting background and font colors on Main Menu and Game Menu manually and automatically
-Supports 4-scale-lightness adjustment ( DS Lite only )
-Supports the Soft Reset.
-Supports Action Replay cheat
-moonshell 1.6 support Software Reset function( Press START key back to the R4 menu)
-DLDI auto-patching
-Full download play support