The Minifon P55 portable wire recorder was manufactured by Protona in Germany in the 1940s-1950s.

The Minifon P55 was originally designed as a portable dictating machine for traveling salesman, the small size being able to fit in a pocket so that it could be taken ‘on the road’. However, this didn’t take off. Instead it achieved much more success as a covert recording device for private investigators and detectives. It had a recording time of one hour, which, compared to other devices on the market at the time, was very long.

The watch microphone was an optional accessory to use with the recorder. When worn, the cord would go up the sleeve and then down the body to connect with the body harness for the Minifon. This feature was particularly popular with cold war spies and PIs who were trying to record covertly.