Reliable Wavin OsmaS PVCU Boss Adaptor BK 50×40 SW/S (2S299B) — a quality 50 × 40 mm PVC‑U plumbing adaptor designed for seamless transitions between pipe sizes in soil, waste and drainage systems. Ideal for above‑ground installations, this boss adaptor ensures secure, leak‑resistant connections for domestic and commercial plumbing projects.