... the environment.3. Light WeightIt weight only 1/3 of cast-iron manhole cover, more expediently transport, install, and rush to ... material, adopts scientist prescription, advanced and perfect technique equipment. The product may be used in -50--+150.6. High PrecisionDue to ... cover and its under. It gets over the problem of cast-iron and cement manhole cover run, jump, sound. It improves ...