Principle of the CMS50D Pulse Oximeter is as follows: Photoelectric Oxyhemoglobin Inspection Technology is adopted in accordance with Capacity Pulse Scanning & Recording Technology,the Pulse Oximeter can be used in measuring the pulse oxygen saturation and pulse rate through finger.The product is suitable for being used in family, hospital, oxygen bar, community healthcare, physical care in sports (It can be used before or after doing sports, and it is not recommended to use the device during the process of having sport) and etc.