Brass Insert Guitar Chicken Head Knob AMP Effect Pointer Knob, 12 Pcs Black 12x Black Chicken Head Knobs Color: Black Size: 13.7mm (height) x 30.7mm (length) x 19.2mm (Bottom diameter) Brass Insert with Set screw Fits 1/4" (6.35mm) diameter pots We will include a free wrench to adjust the screw Package Includes: 12 Guitar Amplifer Knobs 1 Wrench