R4 cartridge

[sandysamual]

R4 cartridge or R4 DS or other varieties such as R4 Revolution are the devices for the Nintendo DS or Nintendo DS LITE and DSI version that allow one to play games, listen to music, read books as well as explore world of other possibilities. It has the same size as that of a regular Nintendo DS cartridge. It also has a slot at the back for insertion of a micro SD card so as to allow storing music, movies and other applications such as firmware and other games according to your choice.