The Linker 3DS card is one of the most popular Nintendo 3DS flashcards, offering great value for money. The R4i is the earlier version of the R4 3DS which works with the Nintendo DSi and DSi XL consoles. The main advantage of the R4 3DS is its support for the latest 3DS firmware and also the constant updates from the R4i-SDHC.com team who manufactures the card.
Once you have chosen which R4 card is right for your needs you will need to pick up a memory card to store media files on, most sites offer these included in bundles, however you can use your own if you have one lying around.
The R4 3DS was created specifically for the 3DS console, but also supports the later 3DS XL and 2DS consoles without any problems. Aswell as this it also supports the earlier DS and DS lite consoles, the DSi and DSi XL consoles.