The Ultrasonic Dog Chaser is the most humane and safe way to deter unfriendly dogs. Using the latest ultrasonic technology, the Dog Chaser produces a discomforting but not harmful, high frequency sound, audible to dogs but not to humans. Helps stop the approach of unwanted dogs at up to 20 feet. Works on cats too! Easy to use: Just point the animal repeller at dog or cat and press the button. This dog repeller is also a useful dog training device when used in conjunction with the verbal or hand command. Includes a belt clip. Frequency Range: 20.000Hz-25.000Hz; 135dB; Effective Range: within 20 feet