Pleatco PSR100-4 Replacement Cartridge for Sta-Rite Posi-Flo 100GPM-TX, 100TX, 100TXR, II PTM100, T-100TX, T-100TXR Open with 12 Concentric Slots 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 25-11/16-by-4-3/16-by-4-3/16-inches Made in the USA