Round fiber glass manhole cover 1.OEM service 2.High strength,save resources 3.Light weight,20 year's history Round fiber glass manhole cover1. High strength:its strength is ten times as rigid PVC, much higher than the absolute strength of aluminum to achieve the level of ordinary steel;2.Corrosion-resistant:it stainless, no mold, no rot, no paint, the ability of many gas, corrosive liquid medium ...