EarthSmart This refrigerator water filter contains a compressed carbon block which provides the tremendous capacity to remove or reduce impurities and sediment that may be present in your drinking water. The carbon block has millions of active sites on its surface and within the structure which can absorb impurities like a sponge, and can adsorb and hold other types of impurities on its surface like a magnet. Additionally, this filter can catalytically breakdown other impurities very similar to the way a catalytic converter works in your automobile. It ensures that you are getting the cleanest and best tasting water possible.