Fulcrum Spoke R3 R3-019 Rear LH Black 4x Spokes+Ni

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