All of the nibs featured on Meisternibs will be compatible with all kit pens.
#5 nibs will work with the smaller kit pens, such as the Jr Gentlemen, Baron, etc.
#6 nibs will work with the larger kit pens, such as the Gentlemen, Majestic, etc.
If you are unsure which you have, a #5 nib will have a feed that is 5mm wide. A #6 nib will have a feed that is 6mm wide.
In many cases, the entire nib housing assembly will screw directly into the existing pen section.
In some cases, disassembly is necessary, which is very easy. Click here for a tutorial.
While nibs featured on Meisternibs do fit numerous production pens that are manufactured by modern pen companies, this is not guaranteed. Contact us to inquire about compatibility with specific pens.