X-Small (10") 5-10lbs such as chihuahuas, malteses, & yorkshire terriers; small (14") 11-30lbs such as beagles, cocker spaniels, & pugs; Medium (20") 31-60lbs such as basset hounds, dalmatians, & boxers; Large (26") 61-100lbs such as German shepherds, labrador retrievers, golden retrievers, dobermans & rottweilers.