... 4Material GradeASTM A36, A1011, A569, Q235, S275JR, SS304, Mild steel & Low carbon steel, etc5Surface TreatmentBlack, self colour, hot dip galvanized, painted ... -1987, Australia: AS1657-1985,Germany: DIN24537-1-2006, Japan:JIS low carbon steel grating drain trench cover (factory)