disc usually has a printed label, sometimes made of paper but often printed or stamped onto the disc itself. Unlike the 31/2-inch floppy disk, most optical discs do not have an integrated protective casing and are therefore susceptible to data transfer problems due to scratches, fingerprints, and other environmental problems. Blu-rays have a coating called durabis that mitigates these problems.

Optical discs have been offered between 7.6 and 30 cm in diameter, with