Oatey 43900 PVC Backwater Valve, 3-Inch Protects low areas or basements from backflow or waste from street sewers. Elastomeric seal in quick action flapper ensures a water tight seal. Threaded access cap incorporates a neoprene seal for positive sealing and can be tightened or removed by hand. Valve hub fits DWV pipe and can be adapted for sewer and drain pipe. 1-1/2-Inch or 2-Inch, 6-Inch x 6-Inch Utility Drain -Inch Fits over 1 1/2-Inch Sch. 40 DWV pipe or into 2-Inch coupling