The #104 Penholder fits nibs #100, #103 and #104.

The Crow Quill Penholder fits nibs #102, #107 and #108.

The Oblique Penholder is for copperplate/Spencerian script with the #101 and #103 nibs.

The Speedball Penholder fits nibs #22B, #56, #99, #101, #512, #513EF and all steel brush nibs.