Nottingham Tactical · Ink Cartridge Guide
Know Your
Ink.
Write Your Story With Us.®
Every NTI pen is built around a specific refill standard — engineered from the ground up around the ink it ships with. Find your pen body below, see what's compatible, and write exactly how you want.
Built for Versatility
Same Precision.
Different Ink.
Three NTI pen bodies. Three refill standards. One commitment to quality. From left to right: the Pilot G2 Full Size (5½"), the Parker Mid-Size (5") — our most popular — and the G2 Mini for the pocket carry crowd. Each body is engineered around the exact ink it ships with.
Note: Compatibility varies by pen body type. NTI sells OEM ink cartridges for each pen — shop our ink here. Additional compatible brands are listed below, though we recommend our OEM ink for peak precision.
Find Your Pen Body
The ink that works best in your NTI pen depends on the pen body it was designed around. Each body type is engineered for a specific refill standard — and we sell the exact OEM ink our pens ship with. Shop NTI ink cartridges here. Additional compatible brands are listed below, though we recommend our OEM ink for peak performance.
Our most universal and most popular pen. At 5 inches, the Parker Mid-Size hits the perfect balance — substantial enough to write comfortably for hours, compact enough for everyday carry. It ships with the Schmidt EasyFlow 9000, the exact hybrid ballpoint this pen was designed around. Smooth, quick-drying, and always ready.
The Most Adaptable Pen in the World!
The NTI Parker Mid-Size is the only pen that fully converts to a mechanical pencil — and back again. The Leadslinger mechanical pencil was designed around the Parker pen body, so they share the same frame. To convert, you simply swap the mechanism, internal cartridge, and tip. The body stays. One frame. Two completely different tools. Zero compromise.
Shop the TiButton → LeadSlinger Conversion Kit ▸Also Compatible With
- Schmidt P900 Ballpoint
- Schmidt P950 Megaline Pressurized
- Fisher Space Pen PR4 (with included adapter)
- Parker Ballpoint / Gel Quink / QuinkFlow
- Uniball Jetstream SXR-600 (0.38 / 0.5 / 0.7mm)
- Monteverde Ballpoint & Soft Roll
- Pelikan Giant Ballpoint 337
- Faber-Castell Ballpoint
- OHTO Needlepoint Ballpoint
- Schneider Express 735 / Slider 755
- Sheaffer T Ballpoint
- NTI doesn't guarantee all listed inks match OEM precision. Our pens are designed around the ink they ship with. Shop NTI ink
At 5½ inches, the Full Size is perfect for any gel ink user. It ships with the Pilot G2 — America's best-selling pen refill — and is built around the Euro-style (G2) format, the most widely supported refill standard in the world. That means access to the broadest selection of gel, rollerball, and hybrid inks from dozens of trusted brands.
Also Compatible With
- Pilot G2 (0.38 / 0.5 / 0.7 / 1.0mm)
- Schmidt 888 Rollerball (Fine)
- Schmidt 588 Rollerball (Medium)
- Monteverde Euro Gel
- Pentel Energel (1mm)
- Pentel Energel Needlepoint (1mm)
- Mont Blanc Fineliner (2mm)
- Mont Blanc Rollerball (2mm)
- Uniball Signo 207 / 307 / RT Gel (2mm)
- Moleskine Roller Pen Gel
- Parker-style refills (with adapter)
- NTI doesn't guarantee all listed inks match OEM precision. Our pens are designed around the ink they ship with. Shop NTI ink
The NTI Mini is built for the EDC pocket carry lover — the pen that's always there when you need it and never in the way when you don't. Small but mighty, it uses the Pilot G2 Mini refill, delivering the same smooth, vibrant gel ink as the full-size G2 in a body made for your pocket.
Compatible Refills
- Pilot G2 Mini 0.7mm Gel Ink
- This is the only compatible refill for the Mini body.
- G2 Mini refills are sold as part of the complete Pilot G2 Mini pen at major retailers — or shop NTI's refill page. Shop NTI ink
About Each Ink Type
The OEM ink for our Parker Mid-Size. A premium hybrid that bridges ballpoint reliability and gel smoothness. Flows without skipping, dries fast, and never bleeds through. Tungsten carbide ball for consistent, long-lasting performance.
- Parker-style body — made for Mid-Size NTI pens
- 1.0mm tungsten carbide tip (medium only)
- Available in black and blue
Best For
Everyday carry, long writing sessions — reliable hybrid ink that never lets you down.
NTI's curated gel option for the Parker Mid-Size. Monteverde is one of the most respected names in premium pen refills — delivering smooth, consistent gel ink with skip-free performance and rich color reproduction across all paper types.
- Parker-style body — fits Mid-Size NTI pens directly
- Smooth, consistent gel formula
- Wide range of colors available
- Medium and fine point options
Best For
Writers who want gel ink smoothness in the Parker Mid-Size body, with a broader color selection.
America's most popular pen refill — and the OEM ink for our Full Size body. Rich, water-based gel ink that glides onto the page with vivid, bold lines. Quick-drying formula means clean writing even for left-handed writers.
- G2 / Euro-style — designed for Full Size NTI pens
- Available in 0.38 / 0.5 / 0.7 / 1.0mm tip sizes
- Quick-drying gel — minimal smear
- Wide range of ink colors
Best For
Note-takers, journalers, and anyone who wants vivid gel ink in a precision machined body.
Originally developed for NASA. Pressurized at 45 psi. Writes upside down, underwater, and in temperatures from −30°F to +250°F. Includes a Parker-style adapter — drops into any Mid-Size NTI pen.
- Writes upside down and in extreme conditions
- ~15,000 ft write-out — 3× a standard ballpoint
- Fine, Medium, and Bold tips available
- Includes Parker adapter for Mid-Size NTI pens
Best For
Tactical and field use — when conditions are extreme, this is the cartridge you need.
The first Jetstream refill in a Parker-style body. Smooth as gel, fast-drying as a ballpoint. Metal-body construction built for daily carry and heavy use.
- Parker-style — fits Mid-Size NTI pens directly
- 0.38 / 0.5 / 0.7mm tip sizes available
- Black ink only
Best For
High-volume writers who need the fastest dry time and sharpest lines from a ballpoint.
The only compatible refill for the NTI Mini — and it delivers exactly what you'd expect from a G2. Same smooth, vivid gel ink. Same bold, clean lines. Built for the pocket carry crowd who refuses to compromise.
- The sole compatible refill for Mini NTI pens
- Smooth, quick-drying gel ink
- 0.7mm medium tip
Best For
EDC pocket carry lovers who want real gel ink performance in the smallest NTI body.
Tip Size Guide
Hairline precision. Best for planners, small handwriting, and technical notation.
Clean, controlled lines. The go-to for journaling, note-taking, and daily carry.
The most popular size globally. Perfect balance of flow and precision.
Expressive, high-contrast lines. Ideal for signatures and quick field notes.
The Right Ink
for Your Story.
Every NTI pen is engineered around the ink it ships with. Start with ours — then explore what else fits your carry.
Shop NTI Ink Shop NTI Pens