The Aqua Flo 41407004 is a GAC carbon quick-change filter, and is the replacement filter for the fourth stage of the QCRO and QCUF RO system. As the 4th-stage of the Aqua Flo Reverse Osmosis system, the 41407004 granular activated carbon filter helps to reduce Chlorine, taste, and odor and acts as a polishing filter to provide the best tasting water possible. Featuring a quick-connect twist and lock design, this GAC carbon filter is easy to change, making service a snap. To keep your system in top shape, change the Aqua Flo 41407004 every 6 to 12 months.