The high-frequency whistle's sound travels large distances, reducing the need for the handler to shout. About Clicker Training: Using the principles of positive reinforcement, iTrainer's clicker training communicates to your pet the specific behavior you desire. The distinct click sound is immediately followed by a small reward, encouraging your pet to repeat the behavior. *** Join the community of over 2,500,000 satisfied users by downloading iTrainer today for FREE! ***