Ducati rear wheel spacer for tyre (tire) balancing.

The larger single swing arm rims make for a huge gap to put onto a tire balancer. The bigger those balancing rigs get, the more they cost.
Mine was for more traditional smaller wheel rims (cheap) and the cones only went to something like 26mm.
This piece bridges the 44mm gap on my monster S2R rims, hinges a little in both directions to hopefully find a center on the wheel, which allows you to center the balancing cone to figure that fun stuff out.
Couple of holes there to use some circlip pli