Watts Premier 560077 EZ RO4 Annual Replacement Filter, 5-pack 5-Piece annual filter pack for the Watts Premier 531418 EZ RO4 reverse osmosis^Fast filter change out with valve in head engineering and quick twist filter replacement^Sanitary quarter turn filter change^5-micron sediment filters to trap dirt, rust, sand , silt and suspended particles^2 high-quality 5-mic carbon block filters to reduce chlorine, bad tastes and odors. 1 final carbon block filter to enhance taste and quality