The Franke 06 is the cartridge to choose, as the alternative to the Franke 03 or Franke 04, if your main concern is reducing limescale and the unpleasant scum that can form on the surface of hot drinks in addition to reducing chlorine to improve taste and odour. The Franke 06 filter cartridge incorporates the latest carbon block combined with ion exchange hardness reduction resin. In addition to removing chlorine the Franke 06 cartridge will also reduce the cosmetic effects associated with hard water, reducing limescale build up in the kettle and the film on the surface of hot drinks. Water hardness varies greatly depending upon location and your Franke 06 filter cartridge will need to be replaced at 3 - 6 monthly intervals depending upon the hardness of your water and the amount you use. IMPORTANT NOTE: The Franke 06 is a push-fit filter cartridge. It is not compatible with the Franke filter housings which accept a Screw Fit filter. The Franke 05 is the limescale reduction filter suitable for use with Franke Screw Fit filter housings.