Hand-held pulse oximeter is a portable, non-invasive medical device that uses light to measure a person's blood oxygen saturation (SpO2) as a percentage and their pulse rate, or heart rate. Typically, these devices are designed to be clipped onto a finger and are used by healthcare professionals or individuals for continuous or spot-check monitoring of a patient's oxygenation levels in various settings, from hospitals to home environments. They are compact, battery-operated, and often feature large LED displays to show the readings, with some models offering features like data recording and audible alarms.