CULLIGAN AquaCleer AC-50 Replacement Pre amp; Post Filters w/ Membrane SET Replacement Split Carbon Pre and Post Filters AND 50 GPD Membrane for Culligan AC-50 RO Systems Carbon Blocks use high activity Coconut Shell powders, Advanced Binder Technology, and a unique compression molding process resulting in industry leading performance and contaminant reduction capabilities. What you get : ( 1 ) Replacement Culligan 5 micron Sediment Pre Filter ( 1 ) Culligan compatible 50 Gallons per Day TFC Membrane ( 1 ) Replacement Culligan Split Block Carbon Pre Membrane Filter ( 1 ) In-Line Carbon Post Polishing Filter w/ 3/8" in and out Quick Connect Fittings Product Features: Coconut Shell Granulated Activated Carbon (GAC) Advanced Binder Technology Unique Compression Molded Process Chlorine Capacity: 3,000 gallons @ 0.50 gpm Replace Every 6 Months or as needed