The driveway alert is a wire free product that works up to a maximum distance of 300 ft clear view from the pir to the base unit the weatherproof pir sensor can be located within the property perimeter garden shed garage outbuilding or even within a vehicle in the event of the pir detecting movement a signal will be sent to the base unit to alert you of the intrusion by a chimetransmitter requires 3 x aaa batteriesreciever requires 3 x c batteries