Enclosure: The FACP parts are usually housed within a durable enclosure to shield them from environmental aspects and unauthorized accessibility. The SBBRKSM easichange® package replaces the discontinued BRK 660MBX optical and 670MBX ionisation smoke alarms and suits on to your existing BRK twist-match alarm baseplate so there is no need https://www.firesense.co.uk/type/addressable-fire-system/addressable-fire-alarm-control-panels/