We used the Intrud Alert at our apartment and it worked like a charm. It comes with the batteries and mounting tape...everything you need to get started! The on/off switch is on the side so you can easily control the alarm without having to remember codes everytime you come and go. The best part is it's only ONE DOLLAR so you can buy one for all your entrances for just a few bucks. If you don't have a Dollar Tree near you, you can buy the Intrud Alert online for $2.50.