1 . the sensor is not triggered by external noise, signals or vibrations.

First, the sensor  detects the vibrations of the glass and listens

for the right frequency for breaking glass. It sends trigger signal to the main

brain of the car alarm when the glass is broken or hit by a hammer.

2. Glass Break Censors use two common types of detection, vibration and

acoustic. The sensors are very simplistic and easy to understand. 

3 .Acoustic detectors work by hearing the noise of breaking glass. 

You may be thinking does the sensor pick up other sounds as well?

The answer is no, acoustic sensors only are tuned to pick up

the sound of breaking glass. The main advantage of these sensors is

the ability to protect  your car by using only one detector

a trigger signal to any connected any car alarm system. with negative trigger

Wiring

RED : +12V or alarm's positive armed output

Black: connect to ground

Blue : connect to instant trigger Aux-input of alarm