Product Description Metal Guitar/Bass Skull Head Control Volume Tone Knob with Inner Hexagon The Control Knobs are made of high-quality materials.  There are 16 grooved thick (18 tooth splined) shafts on the potentiometer. The threads inside are plastic and the outside is metal.  They are wear-resistant, durable and not easy to damage. They are the long-term partner of the guitar. It is suitable for most electric guitars and provides convenience for music lovers. Let instrument lovers enjoy DIY. High quality metal skull head guitar knobs. Use these skull knobs to dress up your electric guitar or replace the dingy or old knobs. Color: Silver, 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: 1/2/3/4 x Guitar knobs 1 x Hex wrench Mini 6-point wrenches are matched with your knob. You can use it to adjust your knob.  As each monitor is different. There will be some color difference between the product picture and the actual one.