Pleatco PDC25-AFS Replacement Cartridge for Dual Core Advanced Filtration System 25 SF Spa Cartridge, 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-2-3/8-by-2-3/8-inches Made in the USA