Dakota Alert Metal Sensing Probe with 50' of Wire No Transmitter Metal detecting replacement probe with 50' of direct burial wire. The probe will detect vehicles moving by and send a signal through the line to the control box, which will sound a whistle. The probe and wire can easily be buried in turf with a shovel or a lawn edger. The Dakota Alert driveway alarm probe will never send you false alarms from animals or the wind as it is only capable of detecting the movement of large metallic vehicles and only then will an alarm signal be triggered. We recommend that you use this driveway sensor with one of the following wireless transmitters: Dakota Alert 3000 Transmitter (600-foot range), Dakota Alert 2500 Transmitter (2500 foot range), MURS Alert Transmitter (4-mile range).