D1 Mini Refill vs. Fountain Pen Nib Widths
Comparing 2 standards across 14 specifications. 14 key differences identified.
The D1 Refill (standardized under ISO 12757-1 as Type D) is a standardized miniature metal-cased ballpoint/gel refill measuring exactly 67.0 mm in length and 2.35 mm in diameter. Friction-fit into internal selector sleeves, it is the universal standard for multi-function pens (3-in-1, 4-in-1), compact pocket pens, and precision stylus combinations.
Fountain Pen Nib Widths are standardized tip grinding grades that determine ink line width, categorized from Extra Fine (EF) to Double Broad (BB) and Calligraphic Stubs (1.1 mm to 1.5 mm). Crucially, Japanese nibs (Pilot, Sailor, Platinum) write approximately one full step finer than Western nibs (Pelikan, Lamy, Kaweco) due to the dense stroke requirements of East Asian kanji characters.
Specification Comparison Table
14 Parameters| Parameter / Spec | ||
|---|---|---|
|
Overall Length
|
67.0 ± 0.5 mm (2.64 in) | — |
|
Outer Tube Diameter
|
2.35 ± 0.05 mm (0.093 in) | — |
|
Mounting Mechanism
|
Friction-fit slide sleeve (no threads or springs attached to refill body) | — |
|
ISO Standard Code
|
ISO 12757-1 Type D | — |
|
Ink Varieties
|
Hybrid low-viscosity (Uni Jetstream SXR-200), Gel (Zebra JSB), standard ballpoint (Lamy M21, Schmidt 635) | — |
|
Benchmark Multi-Pens
|
Lamy 2000 4-Color, Rotring 600 3-in-1, Zebra Sharbo X, Kaweco Liliput ballpoint | — |
|
Extra Fine (EF)–Japanese
|
— | Approx. 0.20 to 0.28 mm line width (hairline precision) |
|
Extra Fine (EF)–Western
|
— | Approx. 0.35 to 0.40 mm line width (similar to Japanese Fine) |
|
Fine (F)–Japanese
|
— | Approx. 0.30 to 0.38 mm line width (standard everyday Japanese notebook writing) |
|
Fine (F)–Western
|
— | Approx. 0.50 to 0.60 mm line width (similar to Japanese Medium) |
|
Medium (M)–Japanese
|
— | Approx. 0.50 to 0.58 mm line width |
|
Medium (M)–Western
|
— | Approx. 0.70 to 0.80 mm line width (plentiful wet ink flow) |
|
Broad (B) & Stub (1.1 / 1.5 mm)
|
— | Broad: 0.9–1.0 mm | Stub: Flat rectangular tip with thick downstrokes and hairline cross-strokes |
|
Tipping Material
|
— | Sintered osmium/iridium/ruthenium platinum-group alloy sphere welded to gold or steel tines |