Product Description The Control Knobs are made of high-quality Acrylic.  Suitable for potentiometers with 16 thick groove (18 tooth spline) shafts. If there are 10 splines on each side, your pots will need 24 fine spines knobs. If there are 8 splines on each side, your pots will need 18 coarse splines knobs. They are wear-resistant, durable and not easy to damage. They are the long-term partner of the guitar. Push on knobs. Color: Transparent, Black, Gold(Optional) Knob size: 19 x 20 x 24mm(DxWxH), inner diameter is 0.6mm (1 / 4 ").  Please take care of the size you need before buying. Package List: 4 x Guitar knobs