Oatey 43908 PVC Backwater Valve, 6-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.