Our 4SR/4SA series submersible pump adopts AISI304 casing and high strength durable floating impellers. Impellers are made of American Noryl material which has the approval of the American Food and Drug Administration(FDA), with high-quality hydraulic design. AISI304 motor base up to NEMA standard, built in AISI304 check valve, AISI304 outlet and built-in strainer.