SONY MO Disk 230MB Unopened (5 Disks x 2 Sets, Total 10 Disks) According to the description: "This disk can be used with 3.5-inch 230MB MO drives that comply with ISO standards." "Please format it with your existing device before use." I kept these for a long time, thinking I might use them someday with music production equipment (samplers) or computers. They are old, as I've had them for many years, so please be aware of that.