National Diversified Sales 1800 18" Black Expandable Catch Basin Drain with 2 Openings is ideal for capturing heavy volumes of surface water and conveying it to drain pipe for proper release downstream. The modular catch basin is easy to assemble, with 4 sides (2 sides, each with an opening, and 2 sides without) and a bottom part. Position sides as desired, attach to the bottom, and seal with silicone. Side openings connect to 3", 4", 6", and 8" drain pipes with appropriate outlet adapter, sold separately. Made of high-impact polystyrene (HIPS) treated with UV inhibitors. Hassle-free limited lifetime warranty guarantees the NDS product is free from defects—or we’ll replace it.