I bought a 4gb micro sd card from radioshack because my 2gb Kingston just wasn't enough memory. It's terrible, do not buy it if you were thinking about it. I learned the hard way. Slowdowns in a lot of games that shouldn't be slowing down. Graphical glitches (random horizontal lines running through the screen). If you try and play emulators with it think again, because those will move abnormally slow as well. Even navagating through the menus in AKAIO is slower than usual. None of those problems occur with my 2gb Kingston so I know it's not my DS or AK2i's fault. Just don't buy it, it's terrible.