... , non-sagging,non-dirt, and easy to install 4) Hot galvanizing standard: China GB/T13912-925) Wrapping: wrapping is as ... , Mild steel & Low carbon steel, etc5Surface TreatmentBlack, self colour, hot dip galvanized, painted, spray coating 6Grating StylePlain / Smooth, Serrated /teeth, ... AS1657-1985,Germany: DIN24537-1-2006, Japan:JIS Durability hot dip galvanised steel grating trench cover (factory)