Flexi disc

The flexi disc (also known as a phonosheet or sonosheet) is a phonograph record made of a thin vinyl sheet with a molded-in spiral stylus groove, and is designed to be playable on a normal phonograph turntable. Flexible records were commercially introduced as the Evatone Soundsheet in 1960, but were previously available in the Soviet Union as roentgenizdat or bones, underground recordings on x-ray plates.

Before the advent of the compact disc, flexi discs were sometimes used as a means to include sound with printed material such as magazines and music instruction books. A flexi disc could be molded with speech or music and bound into the text with a perforated seam, at very little cost and without any requirement for a hard binding. One problem with using the thinner vinyl was that the stylus's weight, combined with the flexi disc's low mass, would sometimes cause the disc to stop spinning on the turntable and become held in place by the stylus. For this reason, most flexi discs had a spot on the face of the disc for a coin, or other small, flat, weighted object to increase the friction with the turntable surface and enforce consistent rotation. If the turntable's surface is not completely flat, it is recommended that the Flexidisc be placed on top of a full sized record.