Functions Description:F1: when the body temperature exceeds alarm temperature(default value is 38°C), will display red backlight and alarm;F2: calibration(default 0), you can set when there is a temperature deviation;F3: alarm switch(ON-OFF), when turn on the alarm, the screen will appear loudspeaker icon;F4: modes selection(default BODY), the screen will display "Body temp" under BODY mode.Backlight Color Description(ONLY BODY MODE):<32°C: red backlight: appear "LO" symbol;32-37.3°C: green backlight: body temperature is normal;37.3-F1: yellow backlight: body temperature is high but not exceed the alarm temperature;>F1: red backlight: body temperature exceeds F1 and alarms.