Tuff Collar Nylon Adjustable Collar - BlueTuff Collars are made from Coastals high quality nylon. The Tuff Collars also feature Coastals unique curved, snap lock buckle which provides added comfort for the pet and convenience for the owner. Great for your growing pet! Made from high quality nylon Unique curved, snap lock buckle Great for growing pets Not to be used for tie out. FOR COLLARS: Measure dogs neck and place 2 fingers between the dog and measuring device for correct length needed.