Fulcrum Spoke R5R-SKB02 Rear Special Spoke 281mm 1

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