Carbon helps reduce contaminants found in drinking water, thanks to a porous surface structure that contaminants bind with in a process called adsorption. This replacement filter has been tested for reduction of 75 contaminants, including lead, chlorine, chloramines, industrial chemicals, cysts, and more. It's designed for use with the Coral Single-Stage Under Sink Carbon Block Water Filtration System (UC100), offering easy, “twist-and-seal” replacement. Your purchase also includes a battery replacement for your faucet's filter change indicator. The Coral water filter reduces contaminants while leaving behind beneficial minerals in your drinking water. These minerals—like potassium, calcium, and magnesium—are essential to the human body. Because they are dissolved solids, these minerals will register on a Total Dissolved Solids (TDS) meter during water testing. Be aware that TDS meters cannot detect most harmful water-soluble contaminants—and a low reading does not mean your water is free of all contaminants.