The Beurer PO30 Pulse Blood Oxygen Monitor is a simple and completely pain free measuring device showing a graphical display of arterial oxygen saturation and heart rate. Oxygen saturation indicates the percentage of hemoglobin in the blood that is loaded with oxygen. Measurements are taken by two rays of light with differing wave lengths on the finger inserted inside the housing. Can be used to detect if there are underlying illnesses such as; cardiac insufficiency, respiratory diseases, asthma or even heart failure. Suitable for sports at high altitudes for example: mountaineering, skiing and aviation sports. Particularly suitable for people with: heart failure, bronchial asthma and chronic obstructive pulmonary diseases.