Four Paws Quick Fit Muzzle For Dogs helps stop biting, barking and chewing, but allows panting and drinking. Its made of strong nylon and is completely washable. The quick fit muzzle doesn't have a lot of buckles that always need adjustments. Only one initial fitting is needed. Helps stop biting, barking and chewing Strong and Copmfortable muzzle allows panting and drinking Fully adjustable quick fit strap and Machine Washable Measure around the snout circumference. To do this, measure your dogs snout by wrapping a measuring tape around it, one half inch below the inside corners of its eyes. The dogs mouth should be closed as you do this; make sure the tape is snug but not tight or too loose. Be a responsible dog owner and do not leave your dog muzzled for long periods. Sizing: Size 0 - Tiny Dogs- Cavaliers, Miniature Dachshunds, Miniature Poodles, Yorkies Size 1 - Jack Russells, King Charles Spaniels, Pugs, Standard Dachshunds, Westies, Whippets Size 2 - Beagles, Border Collies, Cocker Spaniels, Springers, Standard Poodles, Dobermans Size 3 - Bull Terriers, Dobermans, German Shepherds, Labradors, Retrievers, Setters, Staffordshires Size 3XL - Boxer type breeds- short snouts Size 4 - Large Dogs- Bloodhounds, Danes Pyreneans, St. Bernards, Wolfhounds Size 5 - Bull Mastiffs, Rottweilers