Alarm systems have warning devices and more often than not an external sounder to supplement any signalling

Internal Speaker-Sounder

The intruder alarm will be fitted with an internal sounder which doubles up as an entry exit low tone sounder and a high pitch sound when in alarm condition 

External Sounder

The external sounder will have tamper devices and its own back up battery so if it is removed from its fixing it will activate the alarm system and even if the wiring is severed the sounder will continue to operate on its own back up supply.

 

 

 

Internal Speaker

 

Justice Fire and Security sounder