Sta-Rite S7M120 System 3 Pool Filter Inner & Outer Modular Media Cartridge Set Replacement Cartridge combo pack for Sta-Rite S7M120 pool filters Contains one large and one small S7M120 replacement cartridges Cartridges incorporate the best filtration technology for balanced flow and care-free operation Small S7M120 Cartridge Model: 25021-0200S Large S7M120 Cartridge Model: 25022-0201S