The Shimano Deore XT M8250 long-cage derailleur paired with a standard 10-51t M8200 cassette (cassette sold separate) gives all types of riders the range and robustness to tackle every trail on the mountain. With built-in Automatic Impact Recovery a new impact-deflecting wedge shape and simple covered-pulley solutions this derailleur stands up to harsh trail impacts and still retains its lightning-quick shifting speed and high level of performance.Di2 technology results in precise and clean wireless shiftingPinpoint ultra-fast shifting and a no-sacrifice 510% gear rangeWide link structure skid-plate design durable aluminum plate and solid pulley add robustness and longevityAutomatic Impact Recovery function instantly returns the derailleur motor to its original position after impactShimano Shadow ES technology delivers a wedge-shaped design that reduces the derailleur's front-facing surface area and eliminates edges that could catch on rocks and rootsTucked safely inside an enclosed space the battery(not included) won't budge even in rough terrain while remaining easily removable for chargingSolid pulley and shielded pulley teeth prevent trail debris from jamming up your flow