The Comfort Trainer's soft, rounded nose band will fit any dog from a Boston Terrier to German Shepherd to Mastiff, and will gently guide your dog's head and help you to quickly train your dog. The head halter conforms to your dog's head shape without irritating the eyes, constricting the jaw or abrading your dog's nose. Because he is comfortable, your dog will acclimate faster and be ready to learn. Why choose the Comfort Trainer Head Halter over other Head Halters: Powerful yet gentle control to deter pulling, biting and barking or for walking multiple dogs; most comfortable head collar on the market; the adjustment will not slip; dogs acclimate to it faster; less chance of abrasion injury; easy to put on and take off; will not irritate your dog's eyes (if sized/fitted properly); will not come off of your dog (if sized/fitted properly). The Comfort Trainer comes complete with instructions for use. Please note: It takes time to teach your dog to be comfortable wearing any head halter. You will receive instructions on how to do this. If you have only minor problems with pulling, you may consider an Easy Walk No-Pull Harness which most dogs prefer to wear over a head halter. Sizing: Size # 1 fits dogs: 5 to 10 lbs, Chihuahua, Yorkshire Terrier breeds. Size # 2 fits dogs: 11 to 25 lbs, Shih Tzu, Miniature Dachshund breeds. Size # 3 fits dogs: 26 to 55 lbs, Border Collie, Cocker Spaniel, Boxers, Small Bulldogs breeds. Size # 4 fits dogs: 56 to 80 lbs, Dalmatian, Medium sized Golden or Labrador breeds. Size # 5 fits dogs: 81 to 100 lbs, Large retriever, Large German Shepherd breeds. Size # 6 fits dogs: 101 to 180 lbs, Great Dane, Mastiff breeds.