This Mains Inter-connectable Carbon Monoxide Detector from CED addresses CO popularly known as the “silent killer” because it is an invisible, odourless, tasteless gas produced when fossil fuels do not burn completely, or are exposed to heat (usually fire). These fuels include: wood, coal, charcoal, oil, natural gas, gasoline, kerosene, and propane. Electrical appliances typically do not produce CO. It comes with the best sensors in the industry; electrochemical sensors. It uses electrodes in chemical solutions that sense changes in electrical currents when carbon monoxide is present, and they sound an alarm.