This HMSF pump is constructed with close-grained cast iron as a rugged, one-piece unit, specially treated to resist corrosion. A drain port provided for easy winterizing. Its automatic pressure regulator is faster-acting and quieter with a design that eliminates "hunting" for correct drive pressure. New improved stem and guide are precisely molded to assure efficient, trouble-free performance on all deep wells. The precision-molded polycarbonate impeller has perfect balance for highest performance and efficiency. Superior insulation materials protect against excessive moisture and contaminants to ensure prolonged motor life.