The R4 3dS card has become very popular thanks to the wide range of features it offers for a relatively low price. Starting at just $10, the R4 DS is designed for the Nintendo DS and DS lite consoles, and allows you to add a micro sd memory chip for storage of files, later an SDHC version was released which allows you to store 32GB of data on a single chip, without the need for further expansion.
DSi and DSi XL console owners should choose the R4i SDHC card, as it allows you to store and playback media files on your console, without the need for an expensive third party media device.
The newest R4 3DS device works with the Nintendo 3DS and 3dS XL consoles, allowing you to playback and save in game progress, thanks to its support for real time saving or RTS.
There are several versions of the R4 available, including the R4i SDHC 3dS RTS, R4i SDHC dual core and R4i-SDHC.