Many smart watches now include a blood pressure sensor and some even measure your oxygen saturation like real oximeters.

But how do these cheap watches compare with FDA-approved devices?

This is the first part where I try a watch claiming to monitor the SpO2 level (Oxygen saturation level)

The CMS50D+ is a pulse oximeter with qualities essential for the detection of sleep apnea and the ongoing monitoring whenever the condition has been already medically confirmed.

Some particularities not available in most devices of that size make this particular model unique.