Roman Fountains RCN-075-P RCN Series 0.75" NPT Poly Cascade Fountain Nozzle, Polypropylene. The RCN Series Cascade Nozzle produces a highly aerated conical water column. It's a one-piece, injection molded polypropylene construction with a (M) N.P.T. connection. The RCN Cascade Nozzle is a water level dependent nozzle.