Knob for 5mm shaft stepper motors with a flatted shaft. I had a few gripes with the stock EZStruder knob (which looks like a gear) in that it was too small of a diameter, was too close to the motor and wasn't easy to tell how fast the motor was turning by watching the knob. So I put this together with a larger diameter, longer body and an eccentric hole pattern that makes it super easy to judge rotational speeds. Should probably drill & tap for a setscrew, the flat doesn't stand up to much abuse (see blue knob in photo).