This wireless indoor sensor will protect any door or window opening. DIY installation is easy and instant with included damage free 3M dual lock adhesive. You can easily add Door/Window Sensors to your tattletale security system at any time. With optional Chime Mode you be notified of door/windows opening and closing while the system is disarmed by a pleasant chime sound. The Home Door/Window Sensor can protect any door or window up to 500’ from the base tattletale unit!