Ever wonder why every time you go to the doctor they put one of these on your finger? In clinical assessments, pulse oximeter measurement is rapidly becoming accepted as a "fifth vital sign" in addition to temperature, blood pressure, pulse and respiratory rate. This clip-on pulse oximeter quickly and accurately measures the oxygen saturation of arterial hemoglobin and your pulse rate. Features backlit LCD display that shows SpO2, PR and pulse bar, one-button operation and auto power off. Carrying case, lanyard and 2 'AAA' batteries included.