There are at least two flash carts that work with 3DS roms on the 3DS, however, the whole thing hinges on having a 3DS system with a firmware of 4.1 to 4.5
http://www.thegamerdepot.com/blog/which...uxe-or-mt-card/ check out the link above to learn more details
it depends on what firmware your 3ds is .Check your 3ds firmware console before purchasing a 3ds game card, for all 3ds game cards only support N3DS/XL FW Stayed on v4.5-4.1.
Currently i would only recommend two cards for you, mt card or gateway 3ds.Gateway 3ds card is the first card that support 3ds games on 3ds console. mt card is the first card that support multi rom features.Now both of them can play 3ds games on V4.1 to V4.5 3ds, both of them have the mutl rom feature. i personally recommend you buy mt card more though gateway looks better on most forums, but from my source, mt card has better tech support and will be always upgradable through the usb. Ordered my MT card from this offical site: http://www.r4depot.com/15-mt-card-playing-3ds-game-multi-3ds-rom-support.html genuine card and fast shipping.
If your N3DS firmware stayed on v4.1-4.5 and all you want is playing 3ds games, then you can buy gateway 3ds, after all ,this is the world's best 3ds game card and you can use it play nds games and gba games on your 3ds at the same time. But if your N3DS firmware higher than v4.5,and r4 card is your favorite, then you can buy r4i gold like this one : http://www.modchipfactory.com/wood-r4i-...s-lite-p-1.html , this is the best r4 card , 100% game compatibility and directly work on all nintendo console with all firmware version.