I have the siren fitted discreetly in my taxi roof sign & I ve the PIR fitted discreetly in my drive way. It triggers when persons enter my drive so it warns them before they proceed to tamper with my taxi which has a alarm too. I m getting a 2nd Navarous unit for my back garden as well. I also have a in-house driveway alert alarm as extra back up so I know when people are on my property. This is an asset & deterant for what I use it for.