[High quality]: Made of 12.9 grade carbon steel, black zinc plated surface treatment, with slightly anti-rust oil on it, it's rust resistance, excessive hardness, sturdy and not smooth to be broken;SpecificationItems: screw and nut and Washer setMaterial: 12.9 grade carbon steelSize: m2 m2.5 m3 m4 m5 m6Rotary direction: right handType: Machine screw