4", Green, Round Structural Foam Polyolefin Grate With UV Inhibitors, Open Surface Is 3.85 SQIN & It's 5.04 GPM, Fits 4" Sewer & Drain Pipe & Fittings, 3" Corrugated Pipe, & 4" Triple Wall Pipe, Recommended For Pedestrians, Bicycles, & Wheel Chair Traffic.