[Adjustable frequency] Different will respond to different frequencies. Our dog training whistle has a nut and screw to adjust the frequency when turning. Pay attention to the dog's reaction to each setting until your dog shows the strongest response [Convenient dog training] This is a good tool to teach your dog to and learn basic skills. Use an ultrasonic whistle to train your dog so you don't need to shout loudly. [Effective dog training] Even if your pet can't see you, your pet can hear it from a whistle 25 meters ! Train your dog with different instructions and ask them to follow your instructions. (Sitting, paws, lying down, up, healed) [Anti-lost whistle] The main body of the dog whistle is coated with stainless steel, and the protective cover prevents dirt, damage and accidental loss. Using our matching black lanyard, it is easy to wear around the neck. [Note] Please note that this puppy training dog whistle will not let your dog understand your instructions immediately. It requires multiple training to let your dog listen to your instructions. Use methods of rewarding positive behavior to make your dog sound like an obedient friend. The training effect is best when the dog is 3 to 7 months old. size: Whistle 8 x 0.7cm Material:High quality copper + nylon lanyard colour:As shown Package Contents: 2 x Whistle 2 x Lanyard Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.