I bought this foot switch to use it with my arranger keyboard for sustain and arranger actions.
It works pretty well, I enjoy having the additional controls provided by the pedal but my big problem is that it does not work without batteries in it.
Previously I had a Boss FS-5U pedal and it worked the same way, I have never used a battery in it (I don't need to have a red light flash every time I press it), but with this one, the pedal does not work at all unless you have a 9V battery in it.
Due to the little light in the pedal, the little 9V battery will discharge in a matter of a few days if you don't unplug the foot switch so quite a few times, I had the bad experience of sitting down in front of my keyboard and realizing that I forgot (again) to unplug the cable and the foot switch won't work until I get a new battery.
The functionality of the product is flawless, I enjoy it a lot but the fact that I have to constantly buy or charge batteries for it in order to work, puts me off, I will buy two additional Boss FS-5U's and link them together