If you will be locating various types of utilities (power, water, sewer, etc.), or will be working on various types of soil (clay, sand, very wet, very dry, etc.), then you will most likely need to use different frequencies. In that case a multiple frequency locator is the best choice. Otherwise a single frequency locator may be sufficient. Lower frequencies travel longer distances and are less likely to ‘jump’ to adjacent utilities, but don’t do well on poor conductors. Higher frequencies do better on poor conductors, but will travel shorter distances and have a tendency to jump to adjacent utilities. Always start with the lowest frequency possible and go up if necessary.