For Maximum Strength, Comfort and Safety Our Guardian Gear Muzzles help stop biting, chewing and barking. Difficult for dogs to remove with their paws. Features Quick-fit catch with fully adjustable strap and 1" comfort strip around snout area. Strong nylon fabric ensures strength and comfort. Machine washable. Guaranteed for life. Measure just above the nose for proper fit. Muzzles are available in the sizes listed below Muzzle Size Fits Snout Sizes Breed Examples : 0 = 4 1/2":- Miniature Dachshunds, Miniature Poodles, Yorkshire Terriers, and similar sized dogs 1 = 5":- Jack Russell Terriers, Standard Dachshunds, West Highland Whites, Whippets, and similar sized dogs 2 = 5 1/2":- Beagles, Border Collies, Cocker Spaniels, Springer Spaniels, Standard Poodles, and similar sized dogs 3 = 6":- Bull Terriers, Dobermans, German Shepherds, Labrador Retrievers, Setters, Staffordshire Bull Terriers, and similar sized dogs 3XL = 10 1/2":- Boxers and similar sized breeds with wide, short snouts 4 = 8":- Bloodhounds, Great Danes, Great Pyrenees, St. Bernards, Wolfhounds, and similar sized dogs 4XL = 10 3/4":- Extra large Bloodhounds, Great Danes, Great Pyrenees, and similar sized dogs 5 = 8 1/4":- Bull Mastiffs, Rottweilers, and similar sized dogs 5XL = 10 1/4" :- Extra large Bull Mastiffs, Rottweilers, and similar sized dogs