The NIBCO 4 in. PVC DWV plug is used in residential and commercial drain, waste and vent systems. The PVC DWV plug features a male NPT thread connection to fit inside a fitting to seal the end of a pipeline or a location where future additions may be made to the piping system. Polyvinyl chloride (PVC) is the most frequently specified of all thermoplastic materials because of its light weight, durability, and cost-effectiveness. Color: White PVC.