Opti-Pet Dog Whistle To Stop Barking - Adjustable Frequency Training Repellent And Deterrent For Dogs - Best Bark Control And Silencer - Train To Come And Other Commands With Ultrasonic Sound Great for stubborn dogs - Tried everything to get your dogs attention? A blow on this ultrasonic whistle at the right frequency will surely get your pets attention when nothing else has seemed to work Neighbors Dog wont stop barking? This whistle is an excellent and safe deterrent to silence him. No more sleepless nights. Train your dog to follow various commands such as sit, come and to change direction by using different patterns for each. Also great for training hunting dogs. Adjustable Frequencies - By simply turning the screw at the end of the whistle, you can adjust the frequency to find the one that your dog responds to. 100% Satisfaction Guaranteed - Customer satisfaction is our top priority which is why if you are not completely happy with the Opti-Pet ultrasonic dog whistle just let us know and we will provide you with a full refund.