... Bolt A: SpecificationMaterial:stainless steel, aluminum,carbon steelSurface Finish:nickel plated,white zinc,black zinc,color zinc,black oxidemetric and inch ... & gaugeM4-M33Surface FinishingZn- Plated,Ni-plated,Passivated,Tin-plated,Sandblast and Anodize,Chromate, Polish,Electro Painting,Black Anodize,Plain,Chrome plated,etc.Heat TreatmentTempering,Hardening ...