Rare 512 byte per sector Magneto Optical Rewritable Media
Made by Mitsubishi for Pinnacle Micro Apex Drives. 
2 boxes of 5 available. 
Each has had one disk unwrapped and checked for functionality. 
4 Disks factory sealed, one not.   Sold by the Box of 5.
Can create DOS / W95 / W98 bootable disks with these.