A pulse oximeter is a medical device that indirectly measures the oxygen saturation of a patients blood (as opposed to measuring oxygen saturation directly through a blood sample) and changes in blood volume in the skin, producing a photoplethysmograph. It is often attached to a medical monitor so staff can see a patients oxygenation at all times. Portable battery-operated pulse oximeters are also available for home blood-oxygen monitoring. To order click on this link: https://www./generic-finger-fingertip-blood-oxygen-meter-spo2-oled-pulse-heart-rate-monitor-oximeter-whitegreen-24930228.html