Product Review

Test the alarm First:
Step 1: press the test button for 5s (A single silence and test button eliminates confusion and allows you to silence and test the alarm easily)
Step 2: the unit will sound 4 beeps every 5s twice & Red LED flashes & LCD display "000" (3 min), that shows the unit in a normal situation.

Low Power warning: 
Carbon Monoxide Alarm alerts you to dangerous carbon monoxide,even in the event of a power outage.
IF the alarm is low power,you can find the situation
Sound:"Chirp" every 30s
LED: Green LED flashes once every 30s & Red LED is flashes
LCD Display: "Ld"

Malfunctioning warning:
IF the Carbon Monoxide Alarm does not work well,you can find the situation
Sound: "Chirp" every 30s
LED: Green LED is not flashes and Red LED is flashes
LCD Display: "Err"

Leaked:
This carbon monoxide detector features a digital display that shows the carbon monoxide level in the room, as well as the unit's power level.
A:level over 999ppm:
Sound: 4 short alarm beeps
LED: Red LED is flashes
LCD Display: "999ppm"

B:30ppm＜ level＜ 999ppm
Sound: 4 short alarm beeps
LED: Red LED is flashes
LCD Display: "actual concentration"

Memory Mode:
If you leave home for long time, if the unit was alarm in this period, you just press the button for several seconds, the green light will flashes once every seconds ans the LCD will display the actual concentration.

Note:
1.Don't press test/reset button while installing batteries. Otherwise, the unit will not work.
2. The unit needs to be tested weekly. Verify the alarm and LED light operation by test the unit once a week. 

What's in the Box 
1 x Alarm
2 x Screws
1 x User Manual