4 x Pack - Franke Triflow Compatible Filter Cartridges By Doulton M15 Ultracarb (NO Import Duty or Taxes to pay on this product) The 4-Pack Franke Compatible FRX-02, FRX02 Triflow Filter Cartridge is the replacement cartridge for Filtration The Doulton W9223021 UltraCarb Franke Filter features a Sterasyl ceramic outer shell and carbon block W9223020 cleanable filter elements are designed to remove suspended solids, pathogenic bacteria At the heart of every Doulton ceramic filter is the Sterasyl silver impregnated ceramic microfilter The Doulton W9223021 features silver locked within the ceramic structure which The Ceramic UltraCarb cartridge can be cleaned and reused many times.