I recently acquired a 2018 Honda NC750S. One of the previous owners mouted an aftermarket center stand, where one of the two mounting screws (including washers) went missing. I found the manual of the stand, and I am currently looking for replacement parts, but there is one part of which I do not know the name nor do I know where to look for a replacement. It looks like two wide washers fused together. The part is identified by the letter "E" in the screenshot below:
(https://www.motea.com/media/montageanleitungen/constands/hauptstaender/981987.pdf)
In the same document, this part is later referred to as "25/14.5/10.5".