Intruder alarms are an essential means of safeguarding school buildings, providing a deterrent to would - be intruders, as well as alerting those nearby, a remote monitoring centre or the police to the presence of an intruder. (educationbusinessuk.net)
Many guard dogs, such as the Neapolitan Mastiff are low - key because they're only expected to be «on» in the presence of an intruder. (floydcountyhumanesociety.com)
Many find it reassuring to have a dog that will consistently alert them to the presence of an intruder. (professorshouse.com)