Don Sullivan Perfect Dog Command Collar Pinch Training Free DVD & Links Included The Perfect Dog Command Collar can help to train your dog not to pull on the leash when going for a walk. Small Size: (Small to Medium Dogs) Min./Max. Neck Diameter - 5.5 to 18.5 (approx. 14 cm - 47 cm) Suitable for puppies, tiny, small, and medium size breeds for example: American Eskimo, Beagle, Bijon, Chihuahua, Dachshund, Pomeranian, Poodle, Shih Tzu, Spaniels / Terriers, Whipppet, also suitable for larger breed puppies. Large Size: Min./Max Neck Diameter  7 to 24 (approx. 17.75 cm - 60.95 cm) Suitable for Large & Extra Large Dogs such as: Akita, Boxer, Chow Chow, Collie, German Shepherd, Great Dane, Husky, Labrador, Labradoodle, Mastiff, Newfoundland, Pitbull, Rottweiler, Setters, Sheepdog, Standard Poodle, Weimaraner