Concrete rings can break during installation and are subject to corrosion.
Plastic sewer rings typically do not crack or corrode. Buy plastic sewer adjusting rings to increase the service life of the product. The next time you drive over a manhole, you just might be driving over recycled plastic. The rings are used to raise manhole covers up to street level after road surfacing. As many as 50 recycled milk jugs and detergent bottles are used to make a single 27-inch plastic sewer ring that can last up to three times as long as a concrete sewer ring.