Material: The training whistle is made of high-quality stainless steel, sturdy and durable. The sound of the whistle is transmitted by ultra waves and will not affect your dog's hearing. It is very suitable for training dogs. Adjustable Frequency: Our ultra dog whistle can reach a finer frequency range that humans can hardly hear, but it is effective for dogs and can train dogs to perform different actions. Anti-lost Design: Our dog whistle includes a high-quality lanyard. It can be hung around the neck and will not be easily lost due to its compact size. Easy Training: Our dog whistle can reliably help stop your dog from barking and assist your pet in learning commands and techniques. It is suitable for sports, hunting, herding, guide dogs, and rescue dogs. Wide Range of Applications: This high-quality small dog whistle is suitable for training small, medium, and large dogs. You can always find the best frequency for your dog.