Filbur DE Grid Set [Pentair Hayward, 12", 24 sq ft, 7 Full + 1 Half] (FC 9520) valpakproducts It gives technicians and experienced It gives technicians and experienced repair buyers a better option when they want to match the pump with a seal designed for a more serious duty cycle This type of replacement is especially useful when the housing remains serviceable and the cartridge itself is the main service item Grid sets are especially valuable during larger service jobs where the whole internal assembly has aged together and a matched replacement is the cleaner long term solution buyers can help preserve internal balance and support more dependable DE filter performance after the rebuild is complete