I'm a single mom and my career does require me to travel occasionally so I bought one of these to use in hotels or motels. I set this unit in my hotel one night and forgot to lock the doors. The people in the room next door were coming back from dinner and started to open my door by mistake. Boy did this thing SCREAM! Not only that, but they only got the door open a crack before the door stop wedge prevented them for opening the door even further. Ever since I saw how it really worked I bought a few more for home. Even though we have one of your digital camera security systems, I make the baby sitter set these when I leave. It gives that "little extra security" edge that makes me feel a little better.