Oxygen Sats

This is a Finger Pulse Oximeter which is a medical device that indirectly monitors the oxygen saturation of a patient's blood and changes in blood volume in the skin.
Useful in the assessment of patients with cardiac or respiratory problems it is frequently used in a variety of medical settings.
Respiration along with adequate hydration and food intake are all essentials for health.
A useful rule to follow is:
Eat some food if you are hungry,
Drink some drink if you are dry,
Go to sleep if you are sleepy,
But don't stop breathing or you'll die.