The Brother Micro Disc was a floppy disc for use in the standalone Brother MD-200 disk drive for use with certain Brother electronic typewriters.
It consists of a 2.5-inch flexible disc in a carrier (rather like a 5.25-inch minifloppy disk). The discs are two-sided, and the cover of the disk leaves a large portion of the magnetic surface exposed when the disk is not in its paper envelope.
The format doesn’t appear to have been very common.
Dimensions: 68.5 mm × 68.5 mm