KAISH 12pcs Raised Vintage Guitar Amplifier Knobs Effect Pedal Chicken Head Knobs Red Material: Plastic with Brass Insert; Total height: 16.3mm; Total length: 30.7mm; Bottom diameter: 19mm Fits 1/4" (6.35mm) shaft pots with set screw Chicken Head Knobs for Effect Pedals or Amplifiers Quality Knobs with Screw Screw