The Glass Break Sensor works with any X10 Security System, including Protector Plus Voice Dialer. When placed on a glass window pane, it detects both the vibrations of breaking glass AND the high frequency sound that breaking glass makes. When detected, it sends a wireless radio frequency signal to the main console triggering the alarm. The dual detection ensures the Glass Break Sensor is not tricked by other noises. Also, a slide switch on the Glass Break Sensor lets you select the sensitivity. The sensor sends a "self-checking" transmission approximately every 90 minutes.