High Quality 304 Stainless Steel provides strength and offers good corrosion resistance in many environments. We also provide four free relevant wrenchs in our sets. Many various sizes of M3 M4 M5 M6 screws with matching nuts and flat washers meet different people’s demands. Transparent plastic case for quick access. Nuts and flat washers expand the contact area and reduce the pressure in order to protect the screws and parts. This kit can be widely used in all kinds of precision machinery industry, classified instruments, instruments, electronic products, household appliances, communication products, locks, lamps, lights, toys, etc.