Features: It is very suitable for guitar bass and amplifier part replacments. Wonderful replacements for old damaged guitar control knobs. Great guitar tools which can provide help in guitar replacment. Made of quality metal material, it is durable and long lasting use. The inner middle hole diameter is about 6mm, easy to use and install. Specifications: Material: Metal Color: Black/Golden/Chrome-color Package Weight: approx.50g Size: approx.1.9x1.9x1.85cm/0.74x0.74x0.73in Inner Hole Diameter: approx.6mm/0.24in (More Size Detail, Please See Photo.) Package Includes: 4Pcs Guitar Volume Tone Control Knobs 1Pc Hex Wrench note: Please allow 1-2cm error due to manual measurement. Please make sure you do not mind before you bid. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thanks!