This water sentinel refrigerator water filter a compressed carbon block which provides marvelous capacity to remove and/or reduce impurities and sediment that may be re-create in your drinking water. The carbon block millions of busy sites on its surface and within the structure which can absorb impurities comparable a mooch, and can absorb and hold otherwise types of impurities on its surface comparable a magnet. Additionally, this filter catalytically breakdown otherwise impurities same same to the way a chemical process converter works in your automobile. These processes that you are getting the cleanest and best tasting water practicable. 90 Day against manufacturer defects from date of sale with invoice. For Customer Service 866-218-8473 .