The ZeptoMetrix NATtrol Flu/RSV/SARS-CoV-2 External Run Control (NATFRC-ERC) is a molecular quality control that enables laboratories to monitor the continued performance of multiplexed respiratory assays. The ERC comprises a line of refrigerated, inactivated whole organism controls designed to quickly, easily, and safely assure that testing instruments are providing accurate results. With targeted concentrations of 15,000 cp/mL for all four analytes, NATFRC-ERC is the latest addition to the ZeptoMetrix respiratory product line.