CEDs are conductive vinyl platters that are 30.0 cm (11.8 in) in diameter. To avoid using the metric system to name their discs, they were called "12 inch discs" even though they were actually slightly smaller. Each side of the disc has grooves that are about 19 miles long and are 37 times smaller than the grooves on a regular phonograph record. When the disc is playing, it spins at about 450 times per minute and each rotation of the disc contained several frames of audio and visual information. 