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

D1 Mini Refill vs. Fountain Pen Cartridges

Comparing 2 standards across 12 specifications. 12 key differences identified.

Comparing:
D1 Mini Refill
Fountain Pen Cartridges

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 →

Proprietary Fountain Pen Cartridges are brand-exclusive ink formats engineered with unique nozzle diameters and collar locking geometries that are incompatible with Standard International pens. Key proprietary systems include Pilot/Namiki (wide 5.5 mm bore), Lamy T10 (stepped collar), Sailor (flared collar), and Platinum (metal ball seal).

View full Fountain Pen Cartridges spec sheet →

Specification Comparison Table

12 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
Pilot / Namiki Cartridge
Length: 59.0 mm | Wide 5.5 mm bore | Capacity: ~0.90 ml (IC-50 / IC-100 / Parallel)
Lamy T10 Cartridge
Length: 68.0 mm | Stepped friction collar | Capacity: ~1.15 ml (Lamy Safari, 2000, Studio)
Sailor Proprietary Cartridge
Length: 48.0 mm | Flared ribbed collar | Capacity: ~1.00 ml (Sailor 1911, Pro Gear)
Platinum Proprietary Cartridge
Length: 65.0 mm | Metal stainless steel sealing ball | Capacity: ~1.20 ml (Century #3776, Preppy)
Parker Quink Cartridge
Length: 76.0 mm | Stepped friction plug with reserve tank | Capacity: ~1.20 ml
Cross Cartridge
Length: 38.0 mm | Narrow tapered mouth (Classic Century vs Townsend / Peerless)