Replacement Cartridge for H2O Natural Shower Filter - High Output Chlorine Removing Showerhead Filtration System & Water Purifier - KDF 55, Calcium Sulfite & Activated Carbon Replacement Cartridge for H2O Natural Shower Filters. Complete Filter Sets are available in our Amazon store. Removes Chlorine, Heavy Metals and Unhealthy Chemicals from your shower water. Easy Installation, no tools required! Filter lasts approximately 6 months or 12,000 gallons.