Features: Install any wheel with a 21 mm bolt or nut. Simply push the bolt down to fit it securely. Enhance the smoothness of the wheel. Protect the bolt head from corrosion. Different colors for you to choose, make the exterior of your car more beautiful. Specifications: Color: Black Material: ABS plastic Standard: 21mm Package size: 16152cm/6.35.90.8cm Weight: 57g/2.01oz Package List: 20 * 21mm Nut Caps 1 * Removal Tool