For Manual mode only, you can spinning sensitivity adjusting knob to adjust the sensitivity. The low-sensitivity mode can more accurately determine field conditions in complex lines. In the high-sensitivity mode, the condition of walls and hidden lines can be detected. Sensor indicators emit green, blue and red lights, and the buzzer alarms at different frequencies (low, mid, high). Visual and audible alarm to secure your safety. Led flashlight design makes you more convenient to work in dim/ dark environment.