Set of two generic black preset roller knobs. Center hole is bored for import 6mm* solid shaft Alpha style pots. Hole for the pot shaft in this knob measures exactly 6mm. 1.5mm Allen head set screw for fixing this knob to the solid pot shaft. I measured 24.93mm diameter, 5.70mm thickness. *I measured 5.95mm on the shaft of the Alpha pots in our stock. Sale is for knobs only, pots are shown as illustration of how the knobs are used.