Falsken FTHT-20RF Heater Treater 20 Replacement Cartridge Replacement Filter for "the Heater Treater 20" Units (Models: FtHT-20-RevFlo & FtHT-20-RevFlo-G) Authentic Filter (1) , Direct from Falsken Water Systems Recommended Replacement Interval of 12 Months Comes Complete with Water Treatment Media, O-Rings, Lubricant and Replacement Instructions Beware of Replicas Who Promise the Same Results but Fail to Deliver