Includes stainless steel filters that are permanently attached and designed to work with hydrocarbon fuels only. The purpose of this product is to remove solid contamination down to 0.005" and free water. Free water is the collection of water molecules in the bottom of gas cans, tanks, or drums formed when fuel is stored. The RFF filter will not remove emulsified water. Install Racor fuel filter/water separators to remove emulsified water from your engine's fuel system.