Shimano SM-RT900 Disc Brake RotorSM RT900 DURA ACE CENTER LOCK Disc Brake Rotor ICE TECHNOLOGIES FREEZA 160 140 mm The pinnacle in stopping power, DURA ACE SM RT900 disc brake rotors deliver consistent braking performance for better control and confidence in race conditions. The ICE TECHNOLOGIES FREEZA rotor significantly reduces heat build up in the brake system to ensure consistent high performance braking even on the steepest downhill stretches. SHIMANO's CENTER LOCK mounting