... quality Specifications1.High erosion resistance 2.Desirable breakage security 3.Shock-resistance 4.Aganist theft 5.SMC ... the base material.The products are shaped like iron plates with a hard texture,and have made ... . Light WeightIt weight only 1/3 of cast-iron manhole cover, more expediently transport, install, and ... under. It gets over the problem of cast-iron and cement manhole cover run, jump, sound. ...