Shimano XT RD-M8200 Mechanical Rear Derailleur SGS - 10-51t Max

From BikeTiresDirect

The most robust Shimano Deore XT mechanical rear derailleur to date promises a reliable robust ride for every discipline. It's based around a modern hanger and a new low-profile wedge-shaped design to avoid impacts on the trail. If it does hit rocks or roots a spring inside the derailleur helps it absorb impact and return to its original position. With a 510 gear range the RD-M8200 derailleur is suitable for every ride be it an enduro race or all-day adventure pair it with a 10-51T cassette for a wider gear range. | Shimano XT RD-M8200 Mechanical Rear Derailleur SGS - 10-51t Max