With the FireAngel W2-CO-10X-EU carbon monoxide detector, you protect yourself and your loved ones from dangerous carbon monoxide. With a detection, a sound of 85 decibels sounds. Connect up to 50 different FireAngel Wi-Safe 2 detectors and make your entire home safe. Test the CO alarm regularly via the test switch on the detector. That way you can be sure that it works. The detector works on a lithium battery and lasts an average of 10 years.