Features: 1. Lightweight and Easy-To-Use. 2. Color LED simultaneously displays for testing value and plethysmogram. 3. Adjust the parameters in friendly menu. 4. Manually adjust the direction of interface. 5. Low battery voltage indicator. 6. Visual alarm function. 7. Automatically switch off while no signal. 8. Standard two AAA 1.5V alkaline batteries support more than 30 hours continuous work. 9. Advanced DSP algorithm inside decreases the influence of motion artifact and improves accuracy of low perfusion. 10. Low perfusion :0.2% Specification: Hemoglobin Saturation Display: 35-100% Pulse Rate Display: 30-250 bpm Power Consumption: < 30 mA (normal) Resolution: Hemoglobin Saturation (SpO2 ): 1 %; Pulse Rate: 1 bpm Measurement Accuracy: Hemoglobin Saturation (SpO2 ): 70 % - 90 %; 2 % unspecified (≤70 %) Pulse Rate: 2 bpm Measurement Performance in Low Perfusion Condition: 0.2 %