microSHIFT Advent MX Pro Rear Derailleur - 10/11-Speed, Clutched, Repairable Aluminum Medium Cage, 50t Max, Black/SilverThe goal of Advent MX was to create a group that would stand up to the hardest 10% of riders, and the microSHIFT engineers delivered. The MX Pro rear derailleur features their most robust linkage ever, with a beefy horizontal parallelogram, IGUS bushings at the pivots, and 33% stronger clutch force. What does that mean? Go ahead and huck to flat. With other creature comforts like sealed bearing pulleys and a fully replaceable aluminum cage assembly,