looking for muffler clamp washers

[mmk]

I am missing two of these shown in my hand. The washer being held is from my Dad's Duke 390.
When I took the muffler off my RC, I did not realize these were washers, I just thought it was one attached piece.
Went riding, and they must have vibrated off.

I have had zero success searching for this part. Anybody can link me to where I can buy these? Hugely appreciated!

 

[John390]

short of dealer, or finding one used, you might just have to find a regular washer that will fit over the bushing/sleeve.