This is the one single brake disc. If you plan to change discs on the entire axle then you should buy two products.
The state of the art drilling of Brembo® Xtra™ brake discs provides a brilliant and efficient performance in any braking condition, to emphasize the driving style of true enthusiasts. It has been developed on the basis of experience with car manufacturers and the racing world. Brembo® X-tra™ line brake discs offers maximum reliability, performance, and safety. The size, shape, and position of every hole for each specific brake rotors have been carefully designed, studied and tested by Brembo® technicians.
08.C172.1X - Brake Disc
