1. Made of copper material, melting point up to 1083 Celsius degree. 2. Good electrical conductivity and thermal conductivity. 3. All contained in a compact and see through compartmented plastic case. 4. Great for sump plugs, water, fuel and hydraulic fittings. 5. A sump plug washer set to suit all types of engines be it Car, Marine, Generators, Machinery and Plant. 6. Size: M5 x 9 x 1 (30 PCS) M6 x 10 x 1 (30 PCS) M6 x 12 x 1 (20 PCS) M8 x 12 x 1 (20 PCS) M8 x 14 x 1 (20 PCS) M10 x 14 x 1 (20 PCS) M12 x 16 x 1 (20 PCS) M12 x 18 x 1.5 (5 PCS) M14 x 18 x 1 (20 PCS)