NDS 771 7" Black Plastic Square Grate, Connects to 6" Spee-D Basin, Pipes, and Fittings helps block these elements in stormwater from getting in so your drain system can run efficiently. Has an open surface area of 13.6 sq. in. and flow rate of 42 GPM; drains moderate flows from lawns, landscaped areas, patios, walkways, and under downspouts. The 7 in. Square Drain Grate fits the 6 in. round Spee-D® Catch Basin Drain, 6 in. sewer and drain pipe & fittings, 6 in. single-wall and dual-wall corrugated pipes, and 6 in. Drain Waste Vent/Schedule 40 pipe. 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.