Kidde Firex Mains Powered Heat Alarm that can be interlinked with up to 23 other Kidde mains alarms, be they ionisation, optical or heat. Once interlinked, the detection of the relevant danger by an individual unit will sound across all the connected alarms. Mains-powered heat alarms can be used throughout the home in humid or dusty environments where an optical or ionisation smoke alarm is unsuitable, e.g. kitchens, loft spaces and garages. The FIREX range requires installation by a professionally qualified electrician and complies with UK Building Regulations for new housing and associated standards (Grade D BS 5839, Part 6).