Open the notepad app on computer (or text editor on Mac) … It appears to by some sort of nylon braided cable, it’s not plastic so it glides over the desk very well. The knob base is solid metal, not plastic. Feels very good in the hands and its matte black. Moving up from there is the knob.
https://www.amazon.com/DROK-Lossless-Computer-Controller-Adjuster/dp/B01MV411BR