Tier1 18.19 in. x 8.69 in. 70 sq. ft. Pool and Spa Filter Cartridge Replacement for PTM70, T-70TX, PSR70-4, FC-2540, UHD-SR70 TIER1-PAS-1515 - The Home Depot
ClearChoice Replacement filter for Sta-Rite WC108-57S2X / Posi-Flo II PTM70 / T-70TX - 4 pack