For Hexagonal Screws and Nuts, 13mm Key Protects against corrosion, impact and damage Easy assembly and disassembly without damage Improve the appearance and finish of screw assemblies Dimensions: 13mm from inner hole to edge, 15mm total height Note: The data are all measured manually, please allow 1-3cm error due to differences in light and display, there may be some color differences, please refer to the actual item received.