Beware of inferior COUNTERFEIT XTR chains, they are epidemic online (EBAY, AMAZON and Aliexpress) costing $45-$60. Some of them even have solid pins A genuine Hollow Pin M9100 XTR chain is $100 or more at most shops.
This is the genuine hollow pin chain with reputation for long life and toughness. Honestly this is the most reliable and long lasting chain I have used, usually 2000 miles before needing replaced. This toughness is clear when sizing it, the pin is very hard to break with chain tool.
(2) New XTR 126L Chains available, $79ea. Genuine, no fakes.
ALSO, low use from a parted out bike that used a 34 x 51T drivetrain, clean and strong. No stretch. Genuine Shimano. Sized to 118 links, comes with quick link. $39
CN-M9100 HG+ Hyperglide technology
ALSO have used 10-51T Shimano XT Microspline Cassette, $39 used, $89 new.
See the "more ads by this user" link for other MTB tires and parts