The Italian basket Dog Muzzle can be used as a training aid to reduce biting, barking, chewing, aggression and will discourage dogs from eating unwanted objects such as rocks & sticks while allowing the dog to pant & drink water. These flexible polyethylene (plastic) basket muzzles feature adjustable leather straps and removable front grills for added comfort and access. They're also able to withstand extreme temperatures without breaking. A. Circumference of the size 4 basket is 9 inches. B. The basket length is 2-1/2 inches. C. The neck strap length (buckle to last hole) is 16 inches. Generally fits breeds such as Border Terrier, Jack Russell Terrier, Miniature Poodle, Miniature Schnauzer & Shetland Sheepdog. PLEASE MEASURE THE DOGS SNOUT. How to measure: Circumference - measure at approximately 1/2" below the eyes go all the way around the snout. Length - measure your dog from the inside corner of one eye to the tip of their nose. Note: order the muzzle that is 3/4" to 1" bigger than the exact circumference of the dogs snout. The circumference listed is the exact circumference of the basket. The baskets circumference must be larger than your dogs snout measurement. If your dogs snout is the exact same size as the dog muzzle, your dog will not be able to open his mouth to pant. Please use common sense when using any dog muzzle. Getting a dog used to a dog muzzle takes time and patience. You will need to gradually introduce the dog to the muzzle.