A Wii Optical Disc is a single (or dual) layered disc, that allows games and other media to be read by the Wii console. A Wii Optical Disc is also used for loading Super Smash Bros. Brawl on the Wii, however in certain circumstances, the disc can be dual layered increasing the maximum amount of data from about 4-5 gigabytes, to 7-8 gigabytes. Some Super Smash Bros. Brawl discs are rounded on the edges, where as some are not. This has no effect on the game, or how many layers the disc has.