Pleatco PA50 Replacement Cartridge for Hayward Star-Clear C500, Pentair Purex CF-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 19-3/4-by-3-by-3-inches Made in the USA