# item.guide
Side-by-Side Comparison Pens, Inks & Leads

D1 Mini Refill vs. Parker G2 Refill

Comparing 2 standards across 11 specifications. 11 key differences identified.

Comparing:
D1 Mini Refill
Parker G2 Refill

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.

View full D1 Mini Refill spec sheet →

The Parker-Style G2 Refill (standardized under ISO 12757-2 Doc G2) is one of the most widely adopted ballpoint and gel pen refill standards. Measuring 98.1 mm in length and 5.8 mm in body diameter with a stepped metal barrel and grooved plastic crown cog, it is used by hundreds of luxury pen brands and custom machined EDC pens.

View full Parker G2 Refill spec sheet →

Specification Comparison Table

11 Parameters
Parameter / Spec
Overall Length
67.0 ± 0.5 mm (2.64 in) 98.1 ± 0.3 mm (3.86 in)
ISO Standard Code
ISO 12757-1 Type D ISO 12757-2 Type G2 (Documentary permanence proof)
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)
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
Main Body Diameter
5.8 ± 0.1 mm (0.228 in)
Stepped Tip Diameter
2.5 mm extending 18.0 mm from barrel shoulder
Crown Cam Geometry
Molded nylon cog crown with 4 radial guide splines for push-button advance mechanisms
Available Ink Formulations
Oil-based ballpoint (Parker QuinkFlow, Schmidt P900), hybrid low-viscosity (Uni Jetstream SXR-600), gel ink (Schneider Gelion+, Itoya)
Pen Brand Compatibility
Parker, Pelikan, Faber-Castell, Rotring (600/800), Retro 51 Tornado, Tactile Turn, Karas Kustoms