Pleatco PWW75-4 Replacement Cartridge for Waterway Pool 75, Leisure Bay WW-50, 1 Cartridge Replacement filter for pool and spa cleaning systems 50% open ABS free flow cores maximize water flow through REEMAY filter media Antimicrobial end caps resist chlorine degradation and provide support to filter material for a longer life span 13-1/4-by-6-by-6-inches Made in the USA