Our 24 Heavy Duty Cover fits Polylok Risers and Corrugated or ribbed pipe. These 24 heavy duty covers are made of HDPE with the highest UV Protection on the market today. They have been tested up to 5,000 lbs. Every cover comes with a factory-installed gasket. These covers will withstand normal residential and light commercial traffic. This cover can be also used with our 24 Basins.