A pulse oximeter is a small device that clips onto your finger and reads your heart rate and blood oxygen level:Pre/post- exercisePre/post-operative conditionsMonitoring conditions such as COPD & asthmaFor a healthy person without other underlying conditions, a reading between 95-100% blood oxygen saturation is normal. For those with an underlying disease or heart conditions, their readings may be lower. If you are concerned by your results, contact your healthcare practitioner.Boxed contents: Main unit, lanyard, carry pouch, instruction manual, 2 x AAA batteries Measures Oxygen Saturation (SpO2)Measures Pulse Rate (PR )Dual colour OLED displayBig font display6 display modesAlarm functionMulti-directional displayPortable and convenient with carry bagLow perfusion: 0.3%2 year warranty