5 Efficiently Training Modes for Any Solutions: This dog bark deterrent features 5 training modes to meet your every need. Fixed ultrasonic frequency(25kHz) is perfect for daily dog training and variable ultrasonic frequency(15kHz-30kHz) to repel vicious dogs and all kinds of control undesirable behaviour 2 flashlight mode used for getting dog attention at night beep mode used for getting dog attention consolidate achieved training results 2 LED torch light mode used for walking at night to light will keep you safe. If your dog is not sensitive to this after a long period of use please change to a different frequency for better results