Don't know it but is a set. Only the two lower nibs are of use....the others are way too fat, and two are for outlined letters.
I have a cheap Manuscrip make with a BBBB that is only good for making Headers and at least one of those nibs is even wider than that.
Look in English Ebay for a 6 nib Osmiroid calligraphy set, if it comes with a pen, it is a cheap feeling pen...one is a sac, so you'd waste money getting it re-sac'ed. How ever the Osmiroid nibs will fit Esterbrooks. I have such a set. All six widths are usable. Still have two Esties too.
You can also get a Lamy Joy/Safari with a 1.5 mm nib, that will write wide enough that you can see what mistakes you make as you learn by copying letters out of a calligraphy book, and you can swap a 1.1 nib in and out of your Safari/Joy.
I was just talking on another post about how little Italic calligraphy is refereed to here....and there is so many great scripts.
Sheaffer made an adequate set, but the Osmiroid is better. I gave my Sheaffer set to my god child, in I had that Osmiroid.
German vintage '50-70 semi-flex stubs and those in oblique give the real thing in On Demand line variation. Modern Oblique is a waste of money for a shadow of line variation. Being too lazy to Hunt for affordable vintage oblique pens, lets you 'hunt' for line variation instead of having it.
www.nibs.com/blog/nibster-writes/nibs-germany & https://www.peter-bo...cts/nib-systems,
The cheapest lessons are from those who learned expensive lessons. Ignorance is best for learning expensive lessons.