The GRx Fingertip Pulse Oximeter is for use in measuring oxygen saturation of arterial haemoglobin ‘SpO2’ (by measuring the absorption of red and infrared light passing through perfused tissue) and pulse rate. Changes in absorption caused by the pulsation of blood in the vascular bed are used to determine oxygen. Users must be over 7 years old, weigh more than 40kg and be in a no-motion state. Bluetooth compatible with the GlucoRx Voyager App for iOS and Android