Spring Nut 1.Material:carbon,staninless steel 2.Surface:Zinc Plated,self colour 3.Thread Size:1/ ... :a) normal strength: made from low carbon steel, C1015, Q235 etcb) high strength: made from high carbon steel such as C1035, C1045, etc, And ... with hardened treatment.-material: carbon steel, stainless steel, SS304, SS316. etc.-3) Surface treatment:plain/self colour, zinc ...