National Diversified Sales D6 6" Ductile Iron Round Duracast Grate, Connects to 6" Spee-D Basin & Drain Pipes is built tough to stand up to the elements. Ductile iron drain grate has an H-20 load rating and is ideal for draining light flows of runoff on parking lots, driveways, plazas, courtyards, small lawns, and landscaped areas. Blocks leaves and debris from entering and clogging drain piping while draining water through; open surface area of 7.0 sq." and flow rate of 22 GPM. The 6" Round Grate connects to the 6" Spee-D® Catch Basin, 6" sewer and drain pipes, and 6" single-wall corrugated pipe for a soil-tight fit. Made of ductile iron. Iron grates will rust over time, forming a protective iron-oxide patina that ages from red-orange to a deep, rich brown. NDS grates are lightly painted black to inhibit rust formation for shipping and storage purposes. Hassle-free limited lifetime warranty guarantees the NDS product is free from defects—or we’ll replace it.