It's stuff like the vid that really makes me doubt my "Precisions are crap" view.
To the point that I bought one a little while ago, and yesterday bought another one.
I am so weak.
But - need 1 for flats and 1 for rounds, surely?
I assume that if the hole is 18mm the diameter of the bushing must be too.
Regular ones are for 11/16 inch which is 17mm hole. So if your bushings are larger than 17mm that will be perfect.
I've found a bit on the Hipshot website that sells thicker bushings.
$4 each - bargain.... but $56 is the cheapest shipping option!
I'll have to find another way!
There are 3/8 inch and 1/2 inch posts.
I've got the large ones.
As it happens I've been doing some more digging and apparently the do sell larger bushings - but it looks like I'll have to get them from the USA as nobody stocks them!