A pulse oximeter is a small device that clips onto your finger and monitors the proportion of oxygenated haemoglobin in the blood. This noninvasive tool clips painlessly on to your fingertip, sending two wavelengths of light through the finger to measure your pulse rate and how much oxygen is in your system. A healthy person normally has blood oxygen saturation levels (SpO2) of 94% to 99% consistently. For patients with mild respiratory diseases, the SpO2 should be 90% or above. Medical advice should be sought if SpO2 levels falls below 90%, which is unacceptable for a prolonged period of time.
For best results your fingernails can't be too long, the testers will not work through printed/acrylic/bright coloured nails. Fingers must be clean and dry.