2 in 1 detector: It can be served as both Smoke detector and carbon monoxide detector alarm to detect the threat from these two harmful chemicals,Very suitable for carbon monoxide gas leakage and fire place, Once the smoke and carbon monoxide detector detects these two gases, they will beep..LCD Display: smoke detector carbon monoxide detector combo LCD digit indicates real-time carbon monoxide (CO) concentration in the surrounding air, as well as the battery levels. A low battery warning （“LB”）lets you know it is time to change the battery; a smoke warning (“HHH”) lets you know that a smoke fire is happening..Three Alarm Mode: 85dB Buzzer & LED & Human Voice Warning. The 85dB loud buzzer with rapid flashing red indicator light will warn you when dangerous smoke or CO concentration is detected. The smoke alarm carbon monoxide alarm will emit clearly human voice warning to warn the kids and the oldster to escape the dangerous..High accuratel sensor: Smoke detectors using high accurate electrochemical sensor, alerts you to carbon monoxide danger and insure the safety of your life. Photoelectric sensor is also equipped to detect smoke accurately while minimizing false alarms..Easy Installation & Widely Used: - CO and smoke detector combo can easy to mount on any wall or ceiling with the included mounting bracket, screws and anchor plugs, No hardwired need. Used for bedroom, living room and any other area with a risk of fire danger.