Pleatco PSR50-4 Sta-Rite Posi-Flo 50GPM-TX, 50TX, 50TXR, T-50TX, T-50TXR, II PTM50, Open with 12 Concentric Slots, 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 13-5/16-by-4-3/16-by-4-3/16-inches Made in the USA