Peace of mind for your family! This patented slide has an on/off switch to activate the audible alarm to alert you when the slide has been even just partially removed. This is important for those who wish to know immediately that there is an attempt to exit as well as enter the pet door.The unique Alarm Slide alerts you when armed slide has been removed. Alarm can be turned on or off at your discretion. Batteries and sensor included. Simple and quick installation.