Rail (625Wh) Shimano bump stopper / Shimano bumper

[mtb_fox]

Hi,
I was faffing around with my Rail and some bit of plastic came off the rear end / derailleur.
Anyone what this is and where it belongs?
Thanks

 

[mtb_fox]

Google lense to the recue: this would be bumper Y3FA59000 which is indeed part of the derailleur.

 

[Stihldog]

Google lense to the recue: this would be bumper Y3FA59000 which is indeed part of the derailleur.

Nice find . Looks like part of the XTR 9100 derailer. I wonder if it’s necessary or just an added protection?

 

[mtb_fox]

It does not seem to be an essential item; Shimano says it contributes to smooth running and reduces damage to the shifting swingarm.
Edit: From the Shimano dealer manual I was able to figure out where it goes; it is an easy replacement so already fixed it.