After checked, found r4i-sdhc card is a good card and wanna to buy, i have a question can i play the DS games on 3DS through r4i-sdhc directly?
yep, it allows you to play ds roms on your 3ds console. The r4i-sdhc is a good card, it gets updates regularly, and it has 100% game compatibility. http://www.r4flashcart.com/9-r4i-sdhc-3ds-rts-flashcart-for-3ds-xl-3ds-dsi-and-ds-lite.html that's the site i use, and I have never had a problem with anything from them and delivery is pretty fast
yes, when you receive the r4i sdhc 3ds card, you can just download the kernel from the official site and then use the card to play ds games on your 3ds console. here is the r4i sdhc 3ds card you need: http://www.dsflashcart.com/r4i-sdhc-3ds-flashcart-for-your-ds-dsi-3ds-p-250.html
of course, you can use r4i-sdhc card to play ds games on your 3ds, suggested you choose r4isdhc rts 3ds, this card can directly work on 3ds and dsi latest firmware, you just need download the latest firmware and unzip it,open the folder and copy the root files into your micro sd card.
yes you can. You should also know that http://www.thegamerdepot.com/r4isdhc-3ds-rts-flashcart-for-3ds-xl3dsdsidslds-p-166.html is the best place for this thing. They're legit and I got my card pretty quick.
remember buy a sd card to save the kernel and ds roms. then use r4i-sdhc card on your 3ds console to play ds games.
I do not think you should choose that card, which always abandon older versions when inventing New versions. The former r4i-sdhc card has been stopped production on May 15th. 2013. It is better to choose R4i gold 3ds or Supercard dstwo. You can see this article for reference: http://game4console.blogspot.jp/2013/09/which-flash-card-should-i-buy.html
Yes, you can play ds games with r4i sdhc 3ds card. And you can buy it from http://3ds-games-cards.com/r4i-sdhc-3ds-card-with-kingston-2gb-microsd-card-p-59.html