I've got a pile of extra ones, or you can use a very thin shim like I do. Some people dont run them at all, to set the impeller back further... but I've found this makes it hard to get the prop off later. Hence the shim I use.
sorry, no... the pile is at home. But the shims I use are 20mm ID
I bought a 20mm last night but it's zinc I was a little concerned with the 20mm it seem to be a little loose. If it's been working for you then I will stick with it, of course in stainless though
I have plenty of them. stop looking.