No alarm installed already there to add onto, or you want stand alone which I dont think jw's example do, they are all intruder alarms, JW?
Why don't you post in trade?
And search trade sure this topic been done though
That said the dreaded Grade 3 for jobs that dont require G3 is a bloody nightmare to explain to some people. Insurance brokers are the worse, followed by customers who think that highly sensitive detectors and door contacts will be fine in their dusty old plastic factory with doors that blow open in a gentle breeze.