Composite resin manhole covers are not made of a single material, but are made of high-performance resins such as unsaturated polyester resin and vinyl resin as the matrix, reinforced with glass fiber, and filled with fillers such as quartz sand, calcium powder, and curing agents. They are formed under high temperature and high pressure through a series of precision processes such as molding and pouring.

Its core characteristic is the absence of metal components, so it is often referred to as a "non-metallic manhole cover" or a "fiberglass manhole cover".