1. First power on
After installing two 1.5V AAA batteries, the buzzer will beep, the alarm will start to warm up, and the display will show a 2-minute countdown.
2. Button function
Press the "Test/Reset" button, the LCD screen will first display "888ppm", the LED will flash and the buzzer will sound an alarm.
3. Peak record
After the alarm, press the "Test/Reset" button for less than 3 seconds to check the alarm concentration.
Press the "Test/Reset" button again to clear.
4. Indicator light
Under normal operating conditions, the green light flashes once every 60 seconds.
5. Low battery indication
When the battery is low, the red light flashes once every 20 seconds, the LCD screen displays "Lb".
6. The carbon monoxide detector is equipped with a test button with alarm memory and reset, and has a fault self-test function (when it fails, the indicator shows yellow)
7. Alarm Standard:When the detected level of carbon monoxide exceeds 30ppm, the alarm screen will light up and display the level of carbon monoxide in the air. When the CO level reaches 100ppm, the detector will immediately sound an 85dB alarm and flash a red LED alarm!
LCD screen display instructions:

‘Err' on the LCD to indicate the unit is malfunctioning.
‘Lb' on the LCD to indicate it low battery and need replacement.
‘999ppm” on the LCD to indicate CO level over 999ppm.
If the CO leakage is less than 999ppm but over 30ppm, it would show its actual concentration.
Specifications:
Sensor type: Electrochemical carbon monoxide sensor
Battery Supply: 2* AAA size 1.5V batteries (not included)
Display: LED digital display
Alarm Indication: LCD display, sound and light tips
Quiescent current:
Alarm Current:
Alarm Sound: 85 decibels
Operation Ambient Condition: 0~50°C,