Formufit 1-1/4 in. Furniture Grade PVC 3-Way Elbow in White (4-Pack) F1143WE-WH-4 - The Home Depot
Furniture Grade Square PVC Pipe and Tube On Available Plastics, Inc.
3-in PVC Sewer and Drain Adapter in the Sewage Pipe & Fittings department at Lowes.com
Rectangular Pvc Ducting For Buried Total Heat Exchanger Rectangular Pvc Duct Ventilation Pipe - Pipes - AliExpress
Kit with 2 rectangular backup boxes | PVC tubes and fittings | Installation material | Products | Central vacuum system for homes, businesses and hotels | Disan
USA SEALING Bulk-RPT-PVC-8 PVC Rectangular Tubes, 1-3/8" Outside Height, 3.346" Outside Width, 6 ft. Long: Amazon.com: Industrial & Scientific