The NIBCO 4 in. x 3 in. PVC DWV Hub x Hub Reducing Coupling is designed for use with DWV piping systems. The coupling can be used to adapt PVC pipe to standard female pipe threads. PVC DWV is easy to install and is joined by solvent cementing or threading. PVC fittings exhibit high corrosion and chemical resistance and will not rust, scale, pit or corrode. Color: White.