Cartridge finder/Waterway Plastics 1 1/2-inch In-Line Filter 25Waterway Plastics · spa filter1 1/2-inch In-Line Filter 25Series1 1/2-inch In-Line FilterModel25TypeSpa filterSame replacement partAlso fits these filtersWaterway Plastics TWM Cartridge Filter 251 cartridge→Waterway Plastics Top-Load Filter 251 cartridge→Waterway Plastics Dyna-Flo Top-Mount Skim Filter 251 cartridge→Waterway Plastics Flo-Pro Skim Filter 251 cartridge→Waterway Plastics TWM Skim Filter 251 cartridge→