Wrist Blood Pressure Monitor with Digital Filter Technology uses a sensor to detect and isolate only the essential pulse oscillation. It helps eliminate other noise factors leading to quick and reliable measurement capability. This also helps avoid over-tightening of the cuff on the wrist. An automatic memory feature allows you to capture 90 readings and save them to track the readings over time. The large LCD display panel shows both blood pressure readings and pulse rate displayed simultaneously. comes with two AAA Alkaline batteries.