Size of slide shoulder washer for Q45 pivot clamp bolt?

Just shipped my bike from a bike shop, and they managed to lose the 2 washers that fit on the slide shoulder bolt of the pivot clamp as discussed from ~9:30-10:10 of the YouTube video for assembly of the Q45 (
). The inner diameter of this washer is 8 mm, but I just spent several hours at Ace Hardware and Lowes and was unable to find a replacement with an outer diameter small enough to fit into the recess on the pivot clamp. Anyone know the exact size of this washer and where I might be able to find a pair?
 
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