NDS 75 4" Green Plastic Atrium Grate, Connects to 4" Drain Pipes and Fittings is designed to get the job done. The domed design rises above the surface of the ground to block debris near the base of the drain grate, while stormwater drains from above. The dome grate has an open surface area of 17.0 sq. in. and flow rate of 52 GPM. Use in mulched landscape beds, natural areas, and window wells to drain moderate flows of excess stormwater. The 4 in. Atrium Grate fits 4 in. sewer and drain pipe & fittings, 4 in. single-wall corrugated pipe, and 4 in. triple-wall 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.