?Product Size?The width of this dogs anti bark collars is 3mm(M), and Length: 20” (suitable for dog's neck within 18"), Please kindly using soft tape to measure your dog’s head and neck to choose the proper size. ?Easy to Use? Special chrome plated clasp for quick release and fastening to put on and take off in a second. The metal strong D-ring rotates 360 degrees to prevent the leash from twisting while the pet is running, provides a more secure connection with leash. ?Safe Material?Our durable thick prong collars are made of high quality metal and are durable, rustproof, and are not easy to break. The surface is very smooth and will not scratch the dog's skin. ?Safe and Hutrless?Metal choke chain for dog. The metal is smooth and round, add the rubber caps, double protection will not cause harm to your pets. And can train them effectively with a gentle sensation. The collar distributes the pressure evenly to ensure your pet doesn't unbearable. ?Scientific & Effective Training? The dog training collar allows you to sharpen your dog’s skill. If he/she doesn’t respond to your command, you can gently pull to train him to respond faste.