Shimano RT-CL900 SS Disc Brake Rotor - 140mm Centerlock Lockring IncludedShimano Dura Ace RT CL900 Disc Brake Rotor with Lockring 140mm CenterLock Silver. The Shimano RT CL900 disc brake rotor provides quiet and consistent braking control for any terrain. Consistent braking performance on any long steep descent thanks to excellent heat dissipation Robust arm shape for quiet operation without sacrificing weight or heat dissipation Heat dissipation paint boosts performance Includes lock ring with internal serration TECH