Connect 3 in. Drain Waste Vent (DWV)/Schedule 40 (SCH40) pipe to 4 in. Sewer and Drain (S&D) pipe with the National Diversified Sales 3P12 3" x 4" White DWV/SCH40 Hub x S&D Hub PVC Increaser/Reducer Adapter. The drain fitting also connects 3 in. DWV/SCH40 pipe to drainage products compatible with 4 in. S&D connections such as select channel drain outlets, drainage grates, and pop-up emitters. This increaser/reducer adapter is used to connect two different pipe types and sizes. The Increaser/Reducer Adapter is made of polyvinyl chloride (PVC) and makes a Hub X Hub solvent-weld connection. Meets applicable ASTM standards. For use in non-pressurized underground sewer and drainage applications; maximum working pressure of 5 psi. Hassle-free limited lifetime warranty guarantees the NDS product is free from defects—or we’ll replace it.