Bosch 25010539 QuietCast Premium Disc Brake Rotor, Front Precision balanced to insure smooth operation with no pedal pulsation OEM style vane configuration provides more efficient heat dissipation, reduces vibration that can cause noise, and extends rotor life G3000 heat-flowed castings provide consistent wear, long life, and quiet operation Bi-metal aluminum and zinc clean-look coating/Alutherm 80 extends the life of the rotor and provides a clean look for today's open wheels OEM style ABS tone ring (on required applications) provides trouble free operation of Antilock Brake and Traction Control systems Outer dimension: 277.9mm