Ensure your under sink quick-connect reverse osmosis (RO) water filtration systems, PQC3RO, PQC4RO and PQC5RO, continue to deliver cleaner and refreshing water with the Vitapur RO Membrane VQCROM. This NSF certified replacement component ensures your RO system continues producing great-tasting drinking water by reducing chemical contaminants such as lead, TDS heavy metals and others. For best system performance, replace this RO membrane every 24 months.