DRIVE-ALERT SENSOR WITH 600 FEET OF CABLE For use with models DA-500, DA-503, and DA-504. Extra sensors may be used when knowledge of vehicle movement in more than one area is desired. The PVC-encased sensor comes with 100 feet of direct burial cable attached. Sensors with additional lengths of cable are available. They monitor a 10 foot radius (20' diameter). The sensor may be placed up to 5,000 feet from the Electronic Master Control. As many as three sensors may be added without loss of sensitivity.