Direct Pool Filter Cartridge Replacement is a versatile and effective option for those in need of a replacement cartridge. Compatible with the UHD-SR100, FC-2550, and WC108-58S2X models, our cartridge also works seamlessly with several other systems, including the Sta-Rite Posi-Flo 100GPM-TX, 100TX, 100TXR, II PTM100, T-100TX, T-100TXR, which feature 12 concentric slots for optimal filtration.