The regulated NSK-A-CE product is designed for use as a calibrator in screening, diagnosis, and monitoring procedures of amino acid metabolic disorders. This is a CE-marked IVD medical device (manufactured according to ISO 13485:2016) that is available only in the European Economic Area (EU and EFTA). The nonregulated NSK-A product, in contrast, is not designed for specific metabolic assessment procedures and is globally available for research applications.