Combo Pack contains two Black Berkey Purification Elements and two Berkey Fluoride Filters;Black Berkey Elements remove 99.999% of viruses, 99.9999% of pathogenic bacteria, chlorine, volatile organic compounds including pesticides and herbicides, and 95% of most heavy metals.;Lifespan for Black Berkey Elements - 6,000 gallons for set of 2;Fluoride filters remove 95% of fluoride. Also reduces levels of Arsenic III and V, MTBEs, and other heavy metal ions;Lifespan for Fluoride Filters: 1,000 gallons or 1 year