IT\'S TIME TO TRAIN YOUR NAUGHTY DOG！ If you have a energetic puppy. You may be troubled with the unruly dog. You may worry how to deal when dog behaves incorrectly. You want to train your dog to respond to other commands and cues, but don\'t know how to do. Why not try our Metal Collar? These chain dog collars can train pets to correct their bad habits in the shortest time , better control the dog\'s direction when walking.You just need to slips it over dog\'s head , clipped back, to go out quickly. It\'s excellent for the training of our very strong big dogs behaviors. 3 Sizes for your choice, fit for Small, Medium & Large dogs. S: diameter 2.0 mm,Chain length 40 cm; M: diameter 3.0 mm,Chain length 55 cm; L: diameter 4.0 mm,Chain length 65 cm. Note: 1. If your dog use harness vest before, and it\'s better to use an ordinary collar first and then use the chain collar slowly. 2. Remember to be kind and clip back when not using for training. 3. Wearing the direction of the chain is important, and it depends on the dog usually go in which side when walking with you.