Accurate,Reliable,Highly Sensitive: Meet the Latest EN 50291-1:2018,Equipped with both photoelectric and electrochemical CO sensors that work independently of each other,When carbon monoxide and smoke rise to alarm levels, CO sensors detects CO, the red LED will flash,the alarm provides loud sound 85-decibel warning when it is discovered.Photoelectric Sensor Detects Smoke,Smoke Detector while minimizing false alarms.Bring you double protection from Uninterrupted protection&large detection range. 2 in 1 Carbon Monoxide Alarm and Smoke Detector, very suitable for carbon monoxide gas leakage and fire place, Once the smoke and carbon monoxide detector detects these two gases, they will beep.Package Contents: 1 X carbon monoxide &Smoke detector, 2 X expansion screws, 2 X anchor plugs, 1 X user manual. LCD Digital Displays: You can use the digital display to see the current CO concentration and the status of the machine's battery level.The screen displays wide range real-time CO levels from 000 to 999PPM,the alert time depend the level of carbon monoxide concentration. Alarm Standard: 50ppm, alert within 60 to 90 minutes; 100ppm, alert within 10 to 40 minutes; 300ppm, alert within 3 minutes. Test Mode Button: Malfunction and low battery warnings allow you to easily know the working status of the alarm; Test button enables (silent mode)you to test the alarm weekly, When encountering a non-emergency situationfalse alarms occur),you can immediately press the test button and the LED light will flash cyclically, indicating that it has entered the silent mode. The LED light flashes once every 10 seconds, indicating that the alarm has entered the silent mode. Quick Easy Installation : Battery operated device Can be easily installed and maintained without the need for an electrician,Easy to mount on any wall or ceiling with the included screws; You Can Hear the low power alarm Whe