Does anyone have a source for 1/4 turn fasteners similar to those used on SW-Motech racks?

I like the way that the SW-Motech racks that I had on my '03 were connected to the bike, and the way that they could be removed...

I want to construct a custom set of racks and use a similar attachment method, but my searches have only come up with light duty 1/4 turn fasteners (eg. Dzus).

I am not looking for replacement fasteners for SW-Motech and will need 'both pieces' -- the bolt and nut -- so to speak. And yes, I know that there are washers and springs, too...

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