... the base material.The products are shaped like iron plates with a hard texture,and have made ... 3. Light WeightIt weight only 1/3 of cast-iron manhole cover, more expediently transport, install, and ... scientist prescription, advanced and perfect technique equipment. The product may be used in -50--+150.6. High ... its under. It gets over the problem of cast-iron and cement manhole cover run, jump, sound. ...