The Voicewriter was a dictation format introduced by Thomas A. Edison Industries in the late 1940s. Unlike Edison's previous cylinder-based dictation machines, this used an almost 7 inch diameter flexible red resin-based disc, labelled as an "Edison Diamond Disc". Like the SoundScriber and Audograph systems, sound was embossed in grooves onto the discs, but unlike these competing disc formats, Voicewriter discs could be played back on a phonograph turntable with a microgroove stylus and a US style adaptor for 7 inch singles (although the speed is slightly-less than 33? rpm). A dictation machine is a sound recording device most commonly used to record speech for later playback or to be typed into print.