With a focus on reducing disc brake rotor heat deformation, the result is a quieter brake performance without sacrificing weight or heat dissipation. Features: Quieter than ever, but with superb, consistent braking performance on any long, steep descents, thanks to excellent heat dissipation The new arm shape is more robust, leading to quieter operation Specs: Series: Ultegra / Deore XT Model ID: RT-CL800 Mount: Center lock Sizes: 140mm, 160mm, 180mm, 203mm Weight: N/A Included Lockring: Internally notched (140mm, 160mm), Externally notched (180mm, 203mm) Compatibility: Compatible with both metal and resin Shimano brake pads