Adjustable Frequencies: Different dogs respond to different frequencies. Our dog training whistle has a nut and a screw which can adjust the frequency when rotated. Note your dog's reaction to each setting until your dog exhibits the strongest reaction. Easy Dog Training: This is a great tool for teaching your dog obedience and learn basic skills. Train your dog with the ultrasonic whistle so you don't have to shout loudly. Effective Dog Training: Your pet can hear the whistle up to 25 feet away, even if he doesn't can't see you. Train your dog with different commands and have him follow your instructions. (Sit, Paw, Lay Down, Up, Heal) Anti-lost Whistle: Dog whistle body is made with stainless steel coating with protective cover to prevent dirt, damage and loss accidental. It is extremely easy to wear around your neck with our matching black lanyard. Note: Please note that this puppy training whistle will not allow your dog to understand your instructions immediately. It requires several trainings so that your dog can listen to your commands. Use the positive behavior approach to make your dog a listening and obedient friend. When the dog is 3-7 months old, the training effect is best.