Product information: Simple and convenient, small, light, easy to carry all the qualities present in this pulsometer. A signal appears on the display to indicate when the battery power is not enough to ensure proper operation. Automatic shutdown after 8 seconds without signal. It is sufficient to insert a finger into the oxymeter to have after a few seconds the values of oxytry and pulses/minute. Two AAA batteries guarantee measurements for about 30 hours. Super-easy to use Simply insert your finger to the probe of this digital ossimeter and press the button to start measuring, and large LED screen allows you to read all the crucial information about the level of oxygen saturation in the bloodstream and. Technical Specifications: Range SpO2: 0 ~ 100% Resolution SpO2: 1% Pulse Frequency Range: 25 ~ 250 bpm Wrist Frequency Resolution: 1 bpm Period Update: 1s Average Time: 8s Display Type: 0.96'' OLED Power: 2 AAA 1.5V