This external alarm connects to the front of your master controller. Look above the key of your controller, if there is not a small head phone jack, you CAN NOT use this box. The controller would have to be modified. The external alarm is basically a buzzer extender. When the buzzer goes off at the master controller it will make the buzzer activate in this box. The box also has a silence button. When checking out, indicate how long you would like the wire (from main electronics to external alarm).