[1][2][3] Similar competing recording technologies are the Gray Audograph and Dictaphone DictaBelt.
The machine can record 15 minutes of dictation on each side of a thin (.01-inch)[3] flexible 6-inch vinyl disc spinning at a rate of 33+1⁄3 RPM, at a density of 200 grooves per inch.
[1] Unlike some other recording technologies of the time, the recording stylus creates the groove not by cutting the vinyl but by embossing (plastically deforming) the surface, leaving no waste plastic chips to get into the mechanical works.
[1][3] The format remained popular for two decades before it was superseded by magnetic tape recorders, due in part to the robustness of the discs and the ease with which they could be mailed.
The soft vinyl medium limited the number of times a disc could be played back without degradation of the audio quality.