Pleatco PAST100 Replacement Cartridge for Astral Terra 100, 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 19-11/16-by-3-3/4-by-3-3/4-inches Made in the USA