Naco PVC 4435-5821 8"x4" Bell Reducer. Naco is the industries leader in manufacturing PVC pipe, fittings and valves. PVC Pipe is designed for both above and below ground DWV (Drain, Waste, Vent) Applications. Pvc is generally used for both commercial and residential plumbing construction. Naco covers your PVC needs in every industry from agriculture to drainage systems. This Naco PVC 4435-5821 8"x4" Bell Reducer features a 4" drop designed to increase pressure flow and improve waste removal.