The DURA-ACE groupset is the result of Shimano's ongoing passion for technology. This is reflected in every single component in the groupset. All components are joined together to work as one, reinforcing each other for unparalleled performance. This is how DURA-ACE achieves ultimate supremacy
The 11-speed DURA-ACE rear derailleur has been redesigned for lighter, quicker operation with the help of low-friction polymer-coated cables. This derailleur is also Direct Mount-equipped offering a stiffer foundation for improved shifting as well as minimizing the chance of frame damage through a crash.
Buying Guide - Handbook
What to look for and things to consider before you buy