Pleatco PCAL100 Replacement Cartridge for Waterway 100, Cal Spas, 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 23-5/8-by-2-1/8-by-2-1/8-inches Made in the USA