The Kidde KIDKS1280UKC smoke alarm can be inter-connected with up to 24 other Kidde alarms (of which 18 can be initiating) so when any single alarm detects smoke ALL alarms will sound thoughout the buliding. The hush button feature allows the temporary silencing of nuisance smoke i.e those caused by cooking or steam. The front loading battery can be replaced without the need to disconnect alarm from the mains. This smoke alarm has a power source 230v ac mains powered with a 9 V. back up battery & is approved to EN14604 by BSI CE.