Pleatco PMA50-2002-F Replacement Cartridge for Master Spas Flat, Eco-Pur Filter, 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 16-1/4-by-8-1/2-inches Made in the USA