Adjustable frequencies dog whistles allow you to easily teach your dog unlimited commands such as stop barking, sit, come, lay down, stay, and more. The dog whistles are small and lightweight, you can take it with you everywhere.Different dogs respond to different frequencies. Our dog training whistle has a nut and screw that would adjust the frequency when turned. It is the right dog whistle to stop barking which you want to have. The voice of the dog whistles are not to be silent, just the voice is quieter. Many people can not hear the sound of this whistle clearly , but the dogs can. Don’t worry about it.