This oximeter is simple to use. Once fingertip is placed in the padded clip and power is switched on, the oximeter will begin measuring blood oxygen levels and pulse. Auto power off function makes it more energy-efficient. Quick measurement: Only take a few seconds to get direct reading from LED screen. Easy to read clear display: Two-color and 4-directional display makes reading easy to view from different angles.(press and hold the button for less than 2s to change the display direction).