ST100 sensor.FEATURES : Double detectors, SMD technology; ; pulse width adjustable; automatic temperature compensation; sensitivity adjustable; convenient mounting. Glass break adjustment: Olace the jumper on JP1 above the Glass mark. Green shock led is constantly ON, now you can adjust the sensitivity by turning the Glass potentiometer clokckwise to decrease sensitivity until the yellow and red leds are lighting for each glass break sound. When the jumper is set for Glass adjustment, only the hight frequency sound of glass breaking is detected.Shock adjustment : Place the jumper on JP1 above the shock mark.Yellow LED is constantly on, now you can adjust the sensitivity by turning the shock potentiometer. Hit gently on the proteceted glass and turn the shock potentiometer clokcwise to increase sensitivity and counterclokckwise to decrease sensitivity until the green and red LEDs are lighting for each glass break sound. When the jumper is set for shock adjustment, only the low frequency of the shock signal prior to glass breaking is detected.