NDS 05 6" Green Plastic Square Grate, Connects to 3" and 4" Drain Pipes and Fittings is a good choice for draining light flows of stormwater from small lawns, landscaped areas, patios, and walkways. Features an open surface area of 10.4 sq. in. and flow rate of 32 GPM. The 6 in. Square Drain Grate connects to 3 in. & 4 in. sewer and drain pipes & fittings, 3 in. & 4 in. single-wall corrugated pipes, and 3 in. & 4 in. triple-wall pipes. 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.