Pleatco PSG13.5 Replacement Cartridge for Saratoga Spas, TSC, MPT, 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 5-15/16-by-1.9-inches Keyed with handle Made in the USA