Used spacers to put a gen 1 aprilia Mille / Falco / Tuono axial wheel with the thinner hub onto a radial brake fork.

Bought from af1 long ago, now discontinued.

Reference :

https://www.apriliaforum.com/forums/showthread.php?238566-brembo-old-wheels-on-new-showa-radial-wich-spacers