Pleatco PWW100-4 Replacement Cartridge for Waterway Pool 100, Leisure Bay WW-100, 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 19-1/4-by 10"overall diameter by 6" inner hole size. Made in the USA