Zoeller M53 - 1/3 HP Cast Iron Submersible Sump Pump with Vertical Float Switch. MODEL 53 • Cast iron switch case, motor & pump housing • Engineered thermoplastic base • Engineered, glass-fi lled, plastic impeller with metal insert • Stainless steel guard & handle • Bearing - lower & upper oil fed cast ironZoeller_53_Spec.pdfMN_53_98_Man.pdf