CO Gas Detector with LED Display Increase your safety at home with this CO detector. Carbon monoxide (CO) is a dangerous, colorless and odorless gas that cannot be perceived by humans. CO detectors are needed when using such things as fireplaces, gas stoves, gas furnaces, oil, wood or tile stoves, and attached garages. This life-saving device is tested according to the strict, current standard EN 50291. As a minimum protection, a CO detector should be installed in every room where a fuel appliance is located. In addition, we recommend using one CO detector per bedroom.