LauraStar - Anti-Scale Water Filter Granules 3 Pack - Go+This anti scale granules refill, 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 Anti scale granules should be replaced when they turn completely brown For use with models: Laurastar Pulse, S7a, S5, S4, S3, Go Plus and S Pure