The Drive-Alert is a multi-purpose, electronic alarm system designed to detect vehicles in driveways, lanes or anywhere knowledge of vehicle movement is desired. The DA-500 kit contains a control unit, sensor with 100' of cable and a remote whistle. Drive-Alert operates by sensing changes in the earth's magnetic field. This magnetic field is disrupted when a metal object passes over and the probe sends a small voltage to the controller. Installation is very simple. The probe is buried 6" deep and parallel to the driveway. The direct bury wire is buried along the driveway and connected to the control unit. The Drive-Alert control unit provides power to the system and provides output to the accessories such as a remote whistle, timer control or alarm panel.