Fulcrum 4-M1-101B Lockring & Washer for AFS Disc 4

To identify the Fulcrum part code that you require, please see the fulcrum parts catalogues avaiaible here:

Fulcrum Spare Parts Catalogues

And if you're not sure what model year the wheel is, you can use the Fulcrum catalogues here:

Fulcrum Wheel Catalogues