... supplier 4.SGS,Rohs Hex Machine Screw Nuts — 18-8 Stainless Steel, CoarseMaterial:stainless steel,steel,copperDia:M2-M20Surface Finish ... ,Electro Painting,Black Anodize,Plain,Chrome plated,Hot Deep Galvanize(H. D. G. ) etc.Heat TreatmentTempering,Hardening,Spheroidizing,Stress ... have the best professional and experienced engineers( more than 8 years in this field) and strict QC and QA systemHave ...