Material: knobs is made of ABS; cap is made of Aluminum Total Height: about 16mm; Outer diameter at the base: about 20mm Fits Amplifiers with 6mm Shaft Pots, these knobs DO not fit 'D' shaft Pots Push on fit, no brass insert or set screw, Aluminum knobs are for equipment or rotary potentiometers, used to replace the dirty, shabby Due to the wide variety of amplifiers and parts in the market, please be sure to verify the diameter of the pots on your AMP before you change the knobs for your amplifier size:Diameter 20mm, height 16mm, inner diameter 6mm Material:ABS, aluminum sheet colour:Black , Golden Package Contents: 15 x rotary knobs Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.