Cartridge finder/Waterway Plastics 1 1/2-inch In-Line Filter 50Waterway Plastics · spa filter1 1/2-inch In-Line Filter 50Series1 1/2-inch In-Line FilterModel50TypeSpa filterSame replacement partAlso fits these filtersWaterway Plastics TWM Cartridge Filter 501 cartridge→Waterway Plastics Top-Load Filter 501 cartridge→Waterway Plastics Dyna-Flo Top-Mount Skim Filter 501 cartridge→Waterway Plastics Ultra Skim Filter 501 cartridge→Waterway Plastics Flo-Pro Skim Filter 501 cartridge→Waterway Plastics TWM Skim Filter 501 cartridge→