No batteries required and no need to hook up an external transmitter or search for access points. Uses new technology embedded into the tape for installation near or above the buried facility providing continuous path location. The markers work independently; if a section of tape is cut or removed, the other markers will continue to provide accurate location unlike tracer wire that when broken or poorly spliced will not work as well. When energized using a 3M Dynatel 7420 Locator, the markers are activated. Tuned to a specific frequency for gas, telco, or water.