Carbon monoxide or CO is a poisonous gas emitted from household items that are defective and as a result are burning fuel incompletely. Common sources of CO include ovens boilers BBQ's open and solid fuel fires gas or paraffin heaters and blocked or broken chimneys and flues. Carbon monoxide cannot be smelt tasted or seen and can be deadly - the only way to be alerted to CO is with an audible CO alarm. FireAngel design their CO detectors in-house and rigorously test them to ensure the highest standard of protection for your family and home. They're also third part certified tested and Kitemark Approved by BSI. Suitable for homes in England Wales NI and Scotland.