Material: Buttons are made of ABS; Cap is made of aluminum Total height: about 16mm; Outer Diameter at Base: Approx 20mm Suitable for amplifiers with 6mm shaft pots, knobs do not fit "D" shaft pots Press fit, no brass insert or set screw, aluminum knobs are for sonic equipment or rotary potentiometers, used to replace the dirty, shabby Due to variety of amplifiers and parts on the market, please make sure to check the diameter of your AMP's potentiometers before changing the knobs on your amplifier. Size: Diameter 20mm, Height 16mm, Inner Diameter 6mm Material: ABS, Aluminum Foil Color: Black, Gold Package Contents: 60 x Rotary Knobs Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in a little different from the real thing. The measurement allowed error is +/- 1-3 cm.