I am talking about the thick one with the coarse threads, and you need a 13mm socket to work it. I have never seen it used on anything else than the Victron busbars.
Have lost a couple down there where the sun dont shine…
If you mean the lynx Busbars: these are M8 not M6. Same with the battery connectors of the various Multiplus.
No these are M6, with outside dimensions as an M8.
Product name is “Victron Busbar 150A 6P + cover”
Just use normal M6 nuts.
It’s not M8 in that case.