Pentair 25022-0225S Large Outer Cartridge Replacement Sta-Rite System 3 SM-Series S8M500 Pool and Spa Cartridge Filter Large outer cartridge replacement Fits Pentair Sta-Rite System 3 SM-Series 25-inch pool and spa cartridge filter model S8M500 291-square feet filtration area Measures 23-1/4-inch length by 23-inch height by 23-inch width