My current favourite for super fine lines in my Bullet Journal- Sakura Pigma Micron! These Sakura fine line pens in numbers 03 & 05 have a firm nib to
SAKURA Pigma Micron Pen Set – StationeryMore
Fineline Pen Starter Set
These fine-point pens feature waterproof, quick drying pigmented ink for permanency and true color reproduction. Use for graphics, drafting, illustration or accounting. Experience smooth, skip-free writing and crisp ink colors that leave consistent lettering and lines every time. The archival ink is chemically stable and fade resistant. It does not smear, feather or bleed-through on most papers.
Pigma Micron 10 Piece Set - Black
Sakura Pigma Micron Pigment Fineliner Pens 0.3/0.5mm/graphic Black
Pigma® Micron™ Fine Line Black Pens, 3ct. By Sakura
Sakura Pigma Micron Marker Pen - Black - 8 Pen Bundle
Pens and Highlighters
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Pigma Micron fineliner set, 8 sizes, black