Technical Parameters Display Mode : double Color OLED display SPO2 measuring range: 35-100% Pulse Ratio:30-240 BPM Pulse Waveform display: bargraph display Battery indication: OLED display Power Requirements: 1.5V(A A A size )Alkali Batteriesí-2 Adaptable range:2.6V-3.6V Working current:í_20mA Resolution: SPO2 : 1% Pulse Rate: 1bpm Accuracy: SPO2 :70% to 100% í+2digits,below 70% unspecified Pulse rate:í+2bpm or í+ 2%(select larger) Measurement at Low Perfusion: The values of SPO2 and pulse rate can be displayed properly when pulse saturation is at 0.4%. Accuracy of SPO2:í+4% Accuracy of Pulse Ratio.í+2BPM or í+2% (Select Larger) Resistance to surrounding light: Deviation is smaller than í+1% between value of Oxyhemoglobin measured in natural lighting indoor condition and present lighting sources and that measured in dark room. Automatic shutdown function: The device will power off automatically within 5 seconds when there is no finger in the device. When working, the display direction can be changed by pressing the button shortly. There are six modes of direction. In working term, long press can change the lighteness of the screen.