5 Pack Dog Whistle [Stable sound output is the most important] If the human ear can hear it, it's not ultrasonic. How can you be sure the whistle is working if you can't hear it? And an ultrasonic whistle isn't right for all dogs. Some dogs won't even blink when they hear what's called an ultrasound. Have fun outdoors with your dogEliminate complicated tone settings and ensure that every dog can hear the whistle. Great for alerting dog or preventing a dog's misbehavior. Have fun stopping dog barkingWouldn't it be fun if you trained your dog to stop barking? bark by yourself? If the dog continues to bark, try establishing a stop command with a whistle and give the dog a command while training him. Reward the dog if he stops all movement and pant. Patience is the real bond between you and your dogSome dogs can be very uncomfortable with ultrasound. The principle of ultrasonic dog barking is to use ultrasonic waves to make dogs feel uncomfortable. A dog air canister/dog bark killer would be better, but can you be that cruel to a dog? 2-in-1 DesignThe whistle is used to issue commands and the clicker is used to give the dog an affirmation after completing the command.