NAF Profeet Rock Hard Keep your horse on its feet with NAF Profeet Rock Hard. Offering a premium hoof hardener, NAF Profeet Rock Hard helps to protect brittle hooves whilst strengthening soft soles and disinfecting frogs. Profeet Rock Hard offers a naturally available sulphur to provide maximum hoof horn integrity. Directions for use: By using the brush provided â€" paint around the lower half of the hoof and allow the liquid to soak into the nail holes and splits. Apply daily for 7-10 days and during periods of wet weather. Read more… Apply weekly thereafter.