Optical smoke sensor for fast response to slow smouldering fires, with reduced nuisance alarms. Powered by a 1-year replaceable 9V battery (included). This alarm conforms to the latest British Standards. It is important to note that further intervention may be required to wake sleeping children. These products fully comply with UK (UKCA) and EU (CE) regulations. All homes in Scotland are now required by law to have ceiling-mounted and interlinked fire alarms, including heat and smoke alarms. The homeowner and/or landlord is responsible for these changes. For smoke alarms that fully comply with new Scottish legislation, see specific product codes.