... compositeround 600mmanyA15, B125,C250,D400composite resin,fiberglass,fabric1.High strength: composite resin,fiberglass as raw material,so strength is high.2 ... .Light weight: the composite manhole cover is lighter than iron manhole cover3.Nice appearance: color is any ,and the color is in the ... material, not simply in the surface of the cover,so it will keep long.4.Safty: composite ...