SONY 5.25"1.3 GB R/ W Magneto Optical Disk, Part # EDM1300C Product Description: SONY" s optical media are 5.25-inch discs compatible with a wide range of optical drives. They"re treated with advanced polycarbonate substrate for extra durability and shock resistance. They support ISO standards and are tested up to 50 years of proven media life thanks to the optimized recording layers and recording particles. Primary Information Media Type - Magneto-Optical disk Media Form Factor - 5.25" Storage Removable Capacity (Native)- 1.3 GB Recording Format -1024 Bytes / Sector Write Speed - 2X