This is a large ABS 4" Threaded Coupling, and you can get a great price at PlumbersStock. ABS Pipe is both lightweight and quiet DWV (Drain, Waste, Vent) Pipe. ABS Pipe is generally used in residential applications such as bathroom fixtures, kitchen appliances, and ventilation systems. ABS Pipe and Fittings, like PVC, are to be glued together for a more reliable seal. This ABS 4" Threaded Coupling features 4" female threads and 4" slip-fit connections. This connection is ideal for appliances and drains with threads. You can easily connect the line to the pipe and thread the other part of the coupling.