Pleatco PFAB50 Replacement Cartridge for Pentair / Pac Fab Mytilus FMY 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 11-1/8-by-3-1/16-byb-3-1/16-inches Made in the USA