Operation principle, function and structure The patient sensor end of the product is attached on the patient's index finger (Thumb, middle finger or others, great toes), and the device connector is connected to compatible monitors or oximeter with SpO2 extension cord. The product adopts 660nm red light and 905nm Infrared light as incident light source, tests light intensity through tissue to obtain SpO2 value as well as pulse rate. Operation principle, function and structure The patient sensor end of the product is attached on the patient's index finger (Thumb, middle finger or others, great toes), and the device connector is connected to compatible monitors or oximeter with SpO2 extension cord. The product adopts 660nm red light and 905nm Infrared light as incident light source, tests light intensity through tissue to obtain SpO2 value as well as pulse rate.