Enhanced Pump Flow & Head: Power: 3HP, 230V; Diameter: 4″ (for 4″ or bigger well casing); Discharge: 1-1/4 NPT. This deep well submersible pump is designed with 18-stage thermoplastic impellers, providing 37GPM max flow and 640 ft max head. It comes with an external control box and a 33 ft electric cord, making life without modern plumbing a lot easier. Pump out your worries with ease and relax. No challenge is too big for you.