The GameCube, like the PlayStation and Dreamcast before it, gets its game data from unwriteable disc media, so, unlike Nintendo's cartridge-based games of yore, you'll need this accessory to save your place in the game, store your preferences, and preserve the stats of your sports games. The GameCube Memory Card 59 is really small--about the size and weight of a poker chip--and comes with 4 MB flash memory (divided into 59 blocks, hence the name), which should be enough to get you started. If you want to archive all your games for posterity, though, you're going to need more than One.