I purchased this online. I made a mistake with the size of the bolt, and it doesn't fit my furniture. Please refer to the photos for the measurements. The diameter of the bolt head, viewed from directly above, is approximately 6mm. This is a set of 4 wooden leg extensions, 5cm high. Small non-slip sheets are also included. I have lost one of the black covers for the bolt. Thank you! The following is the product description that was provided: [Wooden Leg Extensions] These wooden leg extensions have a natural look that easily blends with any interior. [Easy Installation] The screw-in installation method, which connects the legs to the furniture with bolts, allows for installation in under 5 minutes. The fixed legs support the furniture, lift it off the ground to prevent moisture, and make cleaning easier. They are very suitable for replacing the legs of sofas, beds, tables, benches, cabinets, etc.