How wide do Bock nibs go? And duo-points mean that when reversed, it writes about a size finer?
Because of the large size of these nibs, they are #8s, they can be made to go wider than "default", up to 1.2 to 1.3 mm as a stub or italic for the B nibs, due to the large size of the tipping material used.
Normally the reverse side is indeed about a size smaller, but it can be made smaller than that as well, 2 sizes smaller is what we will do, but it can also be made into an italic if s required.
We have been known to create double left footed obliques, i.e, LFO when writing normal, and LFO when writing in reverse (think about that! ), and although that theoretically would be impossible, with the right amount of tipping, the right tools, and a lot of patience, that can actually be done too .
In short, there are lots of possibilities for nib modifications .
HTH, warm regards, Wim