“Great underpowered micro controller running CircuitPython that read a tiny linear potentiometer, sense if you touch the tip and change the color of two neopixels.
You can add a slider to your PC (mac or Linux) and program it as a midi device, or do keyboard emulation, ....
It is a rare item because Adafruit only did a few for a one time run, so getting it still in stock from Pimoroni is a great pleasure.
The only drawback (that's why 4 rather than 5 stars) is that it fit directly into a USB port, but if you move it too hard, it disconnect. My solution is to attach that to a USB extension cord so that it does not stick from the computer and can be moved, also making the connection stronger by attaching it.”