The anti-scale water filter cartridge, specially designed by Laurastar Swiss engineers, allows you to filter tap water before it is used for ironing By preventing limescale, it prolongs the life of your iron. By filtering salts, it improves steam quality. Anti-corrosive, it also prevents damage to boiler components. The cartridge should be replaced when the red light on your station is flashing. For use with models: Laurastar Lift Xtra, Lift Plus, and Lift.