Help to identify this cable

Help to identify this cable. It looks like attenuator cable but it is not.

There are two markings in the middle : “M” and “1”.

It looks like some sort of splitter cable (Stereo mini-jack socket to 2 stereo mini-jack plugs).
Possibly intended for recording from a mobile phone / MP3 player to a computer (connecting the headphone output of a player to the line input of a computer + headphones).

You would need a mini-jack plug and a test meter to know for sure. There could be anything, or nothing inside that middle bit.

Usually splitter has one male plug and two female jacks. :question:

You could try one plug at a time with headphones to see what happens…

If it’s not a simple splitter I’d guess it adapts a “modern” 1-plug TRRS headset to a computer with separate mic & headphone connections. But in that case I’d expect the plugs to be color-coded or marked.