Pleatco PMAX50-XP4 Replacement Cartridge for Maax Spas of Canada, 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 8-7/16-by-1.9-inches Keyed with handle Made in the USA