D1 Mini Refill
Pens, Inks & Leads · 6 specs
Direct Answer
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.
Source: ISO 12757-1:1998 (Ball point pens — Part 1: General use) / DIN 16554 Type D · Last reviewed Aug 28, 2026
Specs
| 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 |
The Multi-Function Pen Powerhouse
Because the D1 refill tube is only 2.35 mm wide, pen manufacturers can fit three or four independent D1 refills plus a 0.5 mm mechanical pencil mechanism inside a single pen barrel controlled by a gravity pendulum selector or rotating cam.