... glass fiber, resin, and quartz so on. Manhole cover, FRP manhole cover, drain cover, cast iron manhole cover, iron ... sewer cover, water supply, building materialsWe specialize in manufacturing FRP/GRP composite manhole covers which are made from glass fiber ... quartz and corundum.Compared with traditional iron manhole cover, our products have advantages as follows: 1. Strictly manufactured according to ...