Microline TFC-335 RO System Replacement Water Filter KitMicroline TFC 335 Complete RO System Replacement Filter Kit Annual service pack with membrane, carbon block, and GAC post filter for the Microline TFC 335 reverse osmosis system 50 GPD Membrane Carbon Block Pre Filter GAC Post Carbon Complete Service Kit This replacement kit includes all three essential filter components for the Microline TFC 335 reverse osmosis system. Replace pre and post carbon filters annually and the membrane every 2 5 years