BIG BLUE 4.5 X 20 Cartridge (refillable) WITH SCALE PREVENTIVE MEDIA 1 LITER (1.5 LBS). BENEFITS PROTECTION FROM SCALE. NO SLIMY SOFT WATER FEEL. TEMPLATE ASSISTED CRYSTALLIZATION (TAC). EFFECTIVE CHEMICAL-FREE SCALE PREVENTION METHOD. BASED ON TAC TECHNOLOGY SPECIAL MEDIA CONVERTS HARDNESS MINERALS INTO HARMLESS, INACTIVE MICROSCOPIC CRYSTALS. This item is in the category “Home & Garden\Kitchen, Dining & Bar\Small Kitchen Appliances\Water Purification\Water Filters”. The seller is “aquatrue” and is located in this country: US. This item can be shipped to United States.