The ACME Silent Dog Whistle 535 is a high-quality, adjustable frequency whistle made of high-impact brass. This canine companion comes with a convenient booklet explaining how to use the whistle, as well as why it's such a fantastic tool for training and behavior modification. Why settle for a regular dog whistle when you can have one that produces a continuous, silent sound? This innovative design eliminates the need for an opponent to hear the whistle, ensuring you can call your canine without them knowing. The whistle is equipped with two distinct air directors, which not only add to the sound but also control its volume, making it perfect for use at various distances. With the ACME Silent Dog Whistle 535, you can effectively train your dog using this silent, yet effective method. Go ahead and give your furry friend the silent treatment today!