Good MaterialThe main body of the dog whistle is made of safe high-quality stainless steel, and the surface is coated with an anti-oxidant protective layer, which is durable, fine workmanship, won't rust and fade. And it doesn't hurt your dog's hearing during training sessions. Adjustable Multi-frequencyDog whistles will not hurt your dogs hearing, the frequency of ultrasonic whistles is adjustable. At first,you can loosen the sound wave adjustment screw, then while blowing into the air inlet, adjust the adjustment lever to the appropriate volume, and finally tighten the sound wave adjustment screw. You can train your dog to listen to different commands in this way. Please note that your dog need to be trained for multiple times to understand your instructions. Safe DesignThis professional dog whistle emits ultrasonic waves that are not easy to detect by human ears but dogs can hear very clearly, so you dont have to worry about any annoying, high-pitched noise. This dog whistles for recall will help you control your dogs barking easily and effectively. Practical & ConvenientThe whistle body is crafted with high quality stainless steel coated with a protective lid to prevent dirt, damage and accidental loss. It is purposely small and lightweight to make it extremely easy to wear around your neck with our matching black lanyard. You also can put it on a key chain or pocket. Focus on the training, it is convenient to free your hands to interact with the dog when training nd make this lightweight dog training whistle part of you. Widely Application: Pet whistle is a good tool to train your dog to sit, come, stop barking, and stay according to your instructions, suitable for poodle, border collie, German shepherd, bulldog, rottweiler, dachshund, huskie, and other breeds. You can also use it for other household purposes, toys or tools.