>>26936973They're basically little DS carts with microSD cards that you put the roms on to and you can emulate DS games, or 3DS games if you get a 3DS one. It can also emulate NES, GB, GBC, GBA, and a couple others on the DS, but it's experimental. They are extremely worth it. I have all of my DS games on one cart instead of carrying around a pouch of 20 cartridges. It is great. It's also a plus being able to play romhacks on the actual DS.
