High quality material: All flat washers are made of copper, high conductivity, corrosion resistant.They have a tighter seal and high heat resistance than steel and rubber washers Good Performance: These most commonly used copper washers have superior rust resistance and excellent oxidation resistance, which can ensure a long life of the screw, excellent for sump plugs, water connections, fueland hydraulics Easy to use: very easy to install, the surface of the washer is smooth to reduce friction between screw and nut, prevent leakage, insulate, prevent loosening or pressure leakage Perfect pack: 165pcs M6 x 10 x 1 x 35pcs, M8 x 13 x 1 metric flat washers are included in this lot x 30pcs, M10 x 14 x 1 x 25pcs, M12 x 16 x 15pcs, M14 x 18 x 15pcs, M16x 1.5 pieces.M18.*24 x 1.5 x 15 pieces, M20 x 26 x 1.5 x 15 pieces Wide Application: High quality high conductivity copper flat washers, perfect for electrical connections on household appliances and commercial, automotive and marine applications where the power source has a threaded/bolted connection