In addition to the primary colouration, an Australian Cattle Dog displays some patches of solid or near-solid colour. In both red and blue dogs, the most common are masks over one or both eyes, a white tip to the tail, a solid spot at the base of the tail, and sometimes solid spots on the body, though these are not desirable in dogs bred for conformation shows. Blue dogs can have tan midway up the legs and extending up the front to breast and throat, with tan on jaws, and tan eyebrows. Both colour forms can have a white "star" on the forehead called the "Bentley Mark", after a legendary dog owned by Tom Bentley. Common miscolours in the Australian Cattle Dog are black hairs in a red-coated dog, including the extreme of a black saddle on a red dog, and extensive tan on the face and body on a blue dog, called "creeping tan". The Cattle Dog has a double coat—the short, straight outer guard hairs are protective in nature, keeping the elements from the dog's skin while the undercoat is short, fine and dense.