【Advantage】The high-pitched sound from the whistle can stop the neighbor's dog from barking without disturbing people, which is conducive to good neighborhood relations. 【Unique Design】This is a whistle with adjustable volume. You can change the volume of the whistle by adjusting the internal space of the whistle. Dog whistle to stop barking silent. 【Multipurpose】This ultrasonic pet training flute can be used for pigeon training, dog training, and cat training. Dog whistles that makes dogs come to you. Dog whistle training. 【Material】This whistle is made of high quality copper metal material, with a good sense of luster, small and delicate, strong and durable.This whistle has a perfect size and a stylish shape that makes it easy to carry. 【Size】The extra long sound waves from the flute can be heard by pets up to three or four kilometers away. Dog Recall Whistle length 2.17 in/5.5 cm. ZBJBinCH 2 Pcs Dog Whistles High Pitch Training Whistles Ultrasonic Copper Core Dog Whistles Silver Dog Training Supplies for Recall and Pet Behavior Control