National Diversified Sales 1830 18" Black Square Low-Profile Adapter Drain, Connects to 3" to 8" Drain Pipes fits in spaces where a traditional catch basin won’t fit; place an 18" catch basin drain grate on top to drain heavy flows from lawns, landscaped areas, parks, driveways, and courtyards and direct excess water to drain pipe. The 18" Low-Profile Adapter connects to drain pipes from 3" to 8" in size with applicable outlet adapter, sold separately. For 8" drain pipes, use outlet adapter (1888); for 6" drain pipes use outlet adapter (1266); and for 3" & 4" drain pipes, use outlet adapters (1242, 1243, or 1245). Low-profile adapter is 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.