The MI-12877 was a cartridge containing thin magnetic wire for recording and playback of audio, and was introduced in 1947 for use in the RCA Magnetic Wire Recorder. Wire was already in use as a recording medium but it was fragile and needed to be threaded across the recording head and attached to a take-up spool. The use of a cartridge made this much easier.

I'm grateful to my friend Thomas for donating this.

For more information, visit https://obsoletemedia.org/mi-12877/

@obsoletemediauk I recently had the opportunity to listen to original magnetic wire recordings and I was amazed how well they preserved the recordings!