KAISH 10pcs Black Guitar Scalloped Edge Amplifier Knob Cylinder Effect Pedal Knobs Guitar Amplifier or Effect Pedal Knobs Dimension: 15.5mm (height) x 12.6mm (Outer diameter); Made of plastic with Set screw ; Fits 1/4" (6.35mm) shaft pots Please be sure to verify the dimensions before you order the knobs