... , SMC , DMC/BMC Manhole covers, gratings,gully tops and Tress grilles, and etc, Which are made from composite material ... advantages:1.Anti-theft, the materials FRP/GRP ,SMC, DMC/BMC are not be used again.2. ... Anti-corrosion, the materials FRP/GRP ,SMC, DMC/BMC have high anti-corrosion.3. Long ... than 30 years). 4.Lighter than cast iron manhole cover 5.Well sealled,no noise pollution or rebound6.High ...