Light and Sound Alarm Warning: The electrochemial CO Monoxide Alarm When a dangerous level of carbon monoxide is detected the red LED will flash and the alarm pattern will sound 85-decibel alarm to protect your family's life loud warning upon detection Alarm Standards: the alert time depend the level of carbon monoxide concentration. 50ppm, alert within 60 to 90 minutes; 100ppm, alert within 10 to 40 minutes; 300ppm, alert within 3 minutes. High Quality CO Alarm, Carbon Monoxide detector equipped with high accuracy and reliable long-life electrochemical CO sensor to detect CO leak quickly Widely Used&Installation Battery operated installs without an electrician , more easily and quikcly mount on any wall or ceiling with included bracket,screws.Used for bedroom,living room ,kitchen room,bathroom,hotel FeaturePower Supply: (DC3V) 2AAA size batteries.(Not included) Sensor TypeElectrochemical Gas Detection TypeCarbon Monoxide Material: ABS Test/Silence button keep you to test it easily.