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In page Samizdat:
"Each disc is a thin, flexible plastic sheet recorded with a spiral groove on one side, playable on a normal phonograph turntable at 78 RPM. They were made from an inexpensive, available material: used X-ray film (hence the name roentgenizdat). Each large rectangular sheet was trimmed into a circle and individually recorded using an improvised recording lathe. The discs and their limited sound quality resemble the mass-produced flexi discs and may have been inspired by it.[citation needed]