NDS 50 6" Green Plastic Round Grate, Connects to 6" Spee-D Basin, Pipes, and Fittings blocks them from entering and potentially clogging the pipeline, as it drains light flows of stormwater from small lawns, landscaped areas, patios, and walkways. Grate has an open surface area of 9.1 sq. in. and a flow rate of 28 GPM. The 6 in. Round Grate connects to the 6 in. Spee-D® Catch Basin, 6 in. sewer and drain pipe & fittings, and 6 in. single-wall corrugated pipe for a soil-tight fit. Made of high-density polyethylene (HDPE) treated with UV inhibitors. Hassle-free limited lifetime warranty guarantees the NDS product is free from defects—or we’ll replace it.