Mini Discs

This handy format was popular in the 90's for storing audio data. Great for portable recording and on-the-go listening. The compact, un-scratchable, re-recordable discs are protected by a hard plastic case and hold up to 74 or 80 minutes of digital audio.

Developed by Sony the format saw the majority of its popularity in Japan. More info here: http://en.wikipedia.org/wiki/MiniDisc