KN-32 Davies Large 1510 D Black Adjusting Knob with 6.0mm/6.4mm shaft hole:
KN-32 oven knob
This type knob is black with white line on the outside for great visibility.
The knob has a M4x0.74 screw which it tightened up onto the pot shaft, so it will work on splined, smooth or D shaped shafts.
These knobs sometimes called oven knobs also often used on guitars, amplifiers and other electronic items.
There are two kinds of shaft for this knob.
6.0mm and 6.4mm shaft, with M14x0.75 set screw.
Black color is available.
KN-32 6.0mm & 6.4mm: