The fingertip pulse-oximeter is used for measuring blood-oxygen levels in the blood. This is used both as a tool for training at specific oxygen levels as well as to ensure user safety. The fingertip pulse-oximeter is ideal for use while sleeping at altitude, training at altitude and Intermittent Hypoxic Breathing (IHB). The fingertip design keeps your hands free while training. -Auto on/off for preserved battery life (2xAAA batteries included) -Digital readout of SpO2 and Heart Rates -Brightly lit LCD for easy viewing in all conditions -Carrying case included. 30 Day No Questions Asked Return Policy.