Carbon MonoxideCOCO Detector High precision and reliable long life electrochemical CO detector to quickly detect CO gas leaks and protect safety Digital display showing battery status and carbon monoxide concentration in the air (ppm) in real timeWhen there is no CO gas in the ambient air, the screen will display 0ppm CO detector with self-test function automatically detects hardware failures such as internal circuit and CO sensor in normal standby -Condition to ensure always correct operation Powered by 3 x 1.5V AA batteries (batteries not included). Low battery warning to alert the user to replace the batteries to ensure full protection. And easy wall or ceiling mounting with accessories Installs in minutes