C.R.I. 3 « & 4 » Silver Line Series submersible pumps are produced with thermoplastic impellers, diffusers and internal check valves. All vital components of these pumps are made of corrosion-resistant thermoplastic material and the shaft is SS 304/431. The pumps are multistage centrifugal type. The best impeller and diffuser design ensure the best possible hydraulic efficiency. The pump is firmly connected to a working submersible electric motor submerged under the water surface. The built-in check valve prevents backflow and reduces the risk of water hammer. All mounting dimensions are suitable for NEMA Standard motors.