Refillable inserts with INDION RS-F de-ionising resin are for use with drinking water systems to remove fluoride and ensure safe levels. Designed for use in one of our filter housings, it can be used in an under-sink drinking water system or as a pre-filtration stage for reverse osmosis water filtration. The media is comprised of opaque off white beads that attract the negatively charged fluoride ions. This is perfect for people concerned about fluoride intake.