Pulse Oximeters are a convenient, non-invasive measuring instrument, which measures the percentage of oxygen saturation in a person's blood (SpO2 ), and their pulse. Simply place your finger on the sensor, and the Pulse Oximeter automatically analyzes the blood. Oxygen and Pulse readings are shown within a matter of seconds. For use at home, hospitals, clinics, and first aid. Available in both Adult and Child models. Both units have a low power consumption and turn off when not in use. The units use 2 'AAA' batteries, which are included.