The security system offers 4 levels of deterrence:

• Yard Sign — Burglar can see from the street, chooses another house
• Warning Decals — If the burglar misses the sign, they can see the
  decals in the windows
• Loud Siren — It can sound loudly when an intruder breaks in
• 24-Hour Monitoring — ADT can send the authorities to your home if
  alarm is not disarmed