This is a premium aluminum guitar knob with a 6mm hole and set screw made to fit all split-shaft and most solid shaft potentiometers. The outer edge of the knob is knurled for ease of use.
Height: 15.5mm
Diameter: 25mm
Mounting hole: 6mm (.236")
If you're looking for a matching kill switch, check out the Red IDO available in 12mm and 16mm.