Pairing the new Deore -RD-M6250 long-cage derailleur with a standard 10-51t cassette (cassette sold separate) gives all types of riders the range and robustness to tackle every trail on the mountain at a more approachable cost. With built-in Automatic Impact Recovery, an impact-deflecting wedge shape, steel plate, and solid pulley, this derailleur stands up to harsh trail impacts, while retaining the precise shifting qualities for which Di2 is known. Other features include integrated on-board battery that's protected by the linkage and easily removable for recharging and connectivity with cycling computers and other third-party devices.