Carbon monoxide gas is created by incomplete combustion of carbonaceous substances such as gas, oil, wood, etc. 
The colorless, tasteless and odorless gas is absorbed very quickly into the blood, causing oxygen deficiency in vital organs such as heart, liver and brain. 
The first physical symptoms of CO poisoning resemble those of the flu: headache, vomiting and fatigue. 
A carbon monoxide detector detects the deadly gas and sounds a loud alarm. 
The XC-series carbon monoxide detectors are high-quality products and function without problems. 
Battery replacement is not necessary. The product contains a non-removable 3V Lithium battery.