The kidde k20c professional series alarms can interlink with up to 23 inter connectible alarms which means that all alarms will sound if any detect smoke or heat detects visible fire particles associated with slow smouldering fires it is 230 volt mains powered with a battery back up in the event of a power failure a hush button allows temporary silencing of nuisance alarms caused by cooking or steam and resets automatically in addition this button is used to check the alarm operation a lock out