A magneto-optical drive is a kind of optical disc drive capable of writing and rewriting data upon a magneto-optical disc. Both 130 mm (5.25 in) and 90 mm (3.5 in) form factors exist. The technology was introduced commercially in 1985. Although optical, they appear as hard disk drives to the operating system and can be formatted with any file system. Magneto-optical drives are common in some countries, such as Japan because of the success of the Sony MiniDisc, but have fallen into disuse in other countries.