The technology used in the Contec CMS50DL, to measure peripheral oxygen saturation, has been assessed, in a general population, according to a non-standard protocol.
Lipnick MS, Feiner JR, Au P, Bernstein M, Bickler PE. The Accuracy of 6 Inexpensive Pulse Oximeters Not Cleared by the Food and Drug Administration: The Possible Global Public Health Implications. Anesth Analg. 2016 Aug;123(2):338-45. doi: 10.1213/ANE.0000000000001300. PMID: 27089002.
Ad Hoc protocol General population (Note: Modified ISO 80601-2-61:2011 study)