The CK135 Car Alarm System a hidden key switch (not included) located inside the car that initially arms this alarm.

Once armed, there will be a short delay allowing the driver to exit the car. Thereafter, opening a door or trunk lid will trigger the alarm and following another short interval (to allow for the driver to enter the car and disable the alarm) the horn will be pulsed at a rate of about once per second. After about 2.5 minutes the alarm circuitry will reset itself, ready for another intrusion. Output handling current: 10A. Supply Voltage 12V car battery. Stand-by power consumption <5mA.