... price & service, ISO9001 Company, MS.Spring +8613512873247Hot dip galvanized steel grating, bar grating, stair treads, trench cover , ... 4'' etc 4Material GradeASTM A36, A1011, A569, Q235, S275JR, SS304, Mild steel & Low carbon steel, etc5Surface TreatmentBlack, self colour, hot dip galvanized ... 1985,Germany: DIN24537-1-2006, Japan:JIS galvanized steel grating, bar grating, stair treads, trench cover ...