Sonys optical media are 3.5-inch discs compatible with a wide range of optical drives. Theyre treated with Sonys advanced polycarbonate substrate for extra durability & shock resistance. They support ISO standards & are tested up to 50 years of proven media life thanks to Sonys optimized recording layers & recording particles. Sony introduced MO media to accommodate a wide range of applications. Sonys original antistatic hard coat protects the disk against scratches & dust, & the shutter is made from a strong, lightweight & wear-resistant aluminum alloy which contains a high magnesium content to maximize smooth disk operation.