Pentair R172500 25 Square Feet Cartridge Replacement, Pool and Spa Dynamic Series II RTL-25 High Flow Top Load Cartridge Filter Cartridge replacement Fits Pentair pool and spa Dynamic Series II top load high flow cartridge filter model RTL 25 This cartridges are manufactured of the finest quality filter media Use for spas, hot tubs, and swimming pools. Measures 16-1/2-inch length by 18-1/2-inch height by 16-1/2-inch width