CD-R
Physical characteristics
A standard CD-R is a 1.2 mm (0.047 in) thick disc made of polycarbonate about 120 mm (5") in diameter. The 120 mm (5") disc has a storage capacity of 74 minutes of audio or 650 Megabytes of data. CD-R/RWs are available with capacities of 80 minutes of audio or 737,280,000 bytes (700 MiB), which they achieve by molding the disc at the tightest allowable tolerances specified in the Orange Book CD-R/CD-RW standards. The engineering margin that was reserved for manufacturing tolerance has been used for data capacity instead, leaving no tolerance for manufacturing; for these discs to be truly compliant with the Orange Book standard, the manufacturing process must be perfect .
CD-R-7