GeoSpec® Brake Rotor Set by Dynamic Friction Company®. Quantity: 4 Per Pack. DFC is excited and proud to introduce our newest short line of premium corrosion-resistant brake rotors - DFC GeoSpec® Coated Brake Rotors. Specially coated with a patented paint to form a durable and attractive silver-gray finish that fights rust far better than other conventional paint or zinc coatings.