This Upper Arm Style Blood Pressure Monitoring Unit is easy to use and maintain. It's compact and highly portable. It operates using 4 AA batteries and has an automatic power-off feature that saves battery life. The easy-to-read LCD digital display shows systolic (top number), diastolic (bottom number) and pulse rate. The onboard memory holds up to 120 check results. This unit uses the Oscillometric Method of determining blood pressure.