Alarm sensor:
IT MEASURES THE AIR PRESSURE INSIDE THE VEHICLE AND IT ALSO MONITORS BY WAY OF A MICROPHONE THE NOISE THAT IS MADE BY EITHER SOMEONE BREAKING A WINDOW OR SCRATCHING YOUR PAINT WORK ECT.
eller
THE WAY IT WORKS IS IT FILLS THE CAR UP WITH A BUBBLE, WHEN THE BUBBLE IS BROKEN LIKE SOMEONE PUTTING THERE HAND IN IT TRIGGERS THE ALARM. IT IS IDEA FOR CABRIOLETS BECAUSE WIND WITH NOT SET THESE OFF SO YOU CAN LEAVE YOUR WINDOWS OR ROOF DOWN AND STILL ARM THE ALARM