High quality: High quality copper, melting point up to 1083, good electrical and thermal conductivity, the insulated washers have stable performance and are insensitive to air, water and temperature. Flat washers are primarily used to relieve pressure and reduce friction. Size: 200 pieces of flat washers, it includes 9 sizes of stainless steel washers to meet different usage needs. (M5 * 9 * 1 30 pieces, M6 * 10 * 1 30 pieces, M6 * 12 * 1 20 pieces, M8 * 12 * 1 20 pieces, M8 * 14 * 1 20 pieces, M10 * 14 * 1 20 pieces, M12 * 16 * 1 20 pieces, M12 * 18 * 1.5 20 pieces, M14 * 18 * 1 20 pieces). Easy to use: They are very easy to install, the smooth surface of the washer can reduce the friction between the fasteners, prevent leakage, isolate, prevent loosening or dispersion of pressure, according to different needs, choose the right size of washer and insert it bolt to tighten the assembly. Wide application: Perfect for electrical connections, home repair, auto repair, machine tools, marine and other vehicles. It is an essential accessory for daily use and work. Good corrosion protection: The washers have a high resistance to rust. Water and oxygen form a greenish-blue patina on the surface of the copper washers. This layer acts as a protective film against rust.