SONY Blu-ray Discs BD-R DL 4X, 10 Pack (2011) Blu-ray phase-change recording film uses inorganic disc less susceptible to ultraviolet rays "hard coat" hardened protective film to prevent scratches proprietary read-write errors that cause adoption Capacity: 50GB / Speed: 1-4X White top, Inkjet printable (22mm-118mm) Quantity: 10 Discs in 5mm cases