Watts Premier 114110 EZ RO4&nbsp;50 GPD Replacement RO Membrane 50-Gallon per day RO membrane 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^Reduces TDS, sodium, arsenic, lead, percholate, radium, uranium, protozoan cysts and more^The heart of your reverse osmosis system reducing impurities down to 1/10,000 of a micron