This does what it says - converts a stereo output to a mono one. There are some caveats though:
- If you are using this for headphones, note that it doesn't mix the two channels into both output channels, it actually outputs mono sound, meaning you only get sound in the left earpiece (both channels mixed). Not a complaint though, since that's what I needed.
- Rotating the connector, there's a 60-80 degree sector that has no signal, or the signal is flaky. This is really bad, since it's not easy to just forget about in case it moves again.
- The connections are really poor - it can slip out quite easily and the female port is quite loose. Not great.
The actual sound quality is fine, when it's connected OK. I would recommend another, better built connector though.