Machine screw with different head type, different surface treatment and different grade. 1.material:carbon steel, alloy steel Item: Machine screwMaterial: Carbon steel, Alloy steel, Stainless steelSize: M3--M64Finish: Zinc plated, Yellow Zinc plated, Zinc Cr+3, Black, Oxidize, HDG, Nylon, Chrome, Nickel, TinHead type: According to customer's requirement