I'd say try to make sure you use a 45mm or 44mm milanese if you can, don't use a 42mm. Series 7 should be 45mm, so if that's what came with your watch, then you should be good.
The lugs (where the band connects to the watch) are shorter/narrower on the 42mm and 44mm milanese loops, which means the metal mesh will sit a lot closer to the watch.
This is how a 42mm milanese loop sits against a 44mm watch:
And this is how a 44mm milanese loop sits against the 44mm watch:
You can see the 44mm version has that extra width between the mesh and watch case, stopping the mesh from scratching up the case. You don't want to scratch up your Ultra.