Pleatco PMA40-2003-R Replacement Cartridge for Master Spas, Down East Round Outer, Eco-Pur, 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 7-3/16-by-4-1/16-by-4-1/16-inches Made in the USA