Material: Copper, These washers are 100% solid Copper. Brass flat brass vein are the highest quality out there, melting point up to 1083°C. Size Types: Quantity: 150Pcs, Different Sizes Flat Washer M5, M6, M7, M8, M10, M10.5, M11, M14, M12, M12.5, M14, M15, M16 , M16.5, M17.5 All contained in a compact, glazed plastic box. Washers are used with nuts and bolts, and provide a larger bearing surface to prevent head nut or bolt from tearing through the attached hardware Flat Washers are arranged in a storage box, allowing you to easily find your way back into the series and avoid loss in the event of needed. Good electrical conductivity and thermal conductivity. Ideal for sump plugs, water, fuel and hydraulic fittings. A sump intake washer is suitable for all types of engines whether car, marine, generators, machinery and factories.