Form Factor
We've designed the Ko-Axis™ with a purpose-built, distinctive shape, sparing no detail. The comfort and ergonomics that were considered in the design phase are unparalleled, resulting in a truly unique writing experience. These features create an aesthetic that turns heads. All of these features have been packed into a pen so thin that it easily hides in any notebook. Be warned: once you write with the Ko-Axis™, you will never go back to a conventional pen.
Actuation
Upon closer inspection of the Ko-Axis™ Rail Pen, you will discover that the aluminum grip slider contains the ink cartridge. By implementing this clever design, it is impossible for the pen to accidentally retract while writing. The ink refill is always present when you need it and never when you don't. We have painstakingly integrated eight ultra-strong neodymium magnets into the end stop positions to ensure perfect engagement, and eliminate any potential for movement of the mechanism while writing.

Writing Experience
The Ko-axis™ isn’t just a beautiful writing instrument, it transforms the act of writing into a wonderful experience. From the first time you extend the ink refill, you’re hooked. The rectangular shape of the Ko-axis™ rests gently in the crease of your hand and lands comfortably in your thumb-and-finger pinch. The shallow divot in the lightly textured slider offers the perfect spot for your pointer to land every time. The weight distribution of the pen was carefully calculated to rest in your hand without applying any torque to your fingers that would tire your hand in a late-night writing session. The Aluminum Edition is the featherlight member of the Ko-Axis™ family. The aluminum body allows the pen to float effortlessly across page after page. The Titanium Edition has 25% more mass than its aluminum brother, providing a solid and comfortable resilience that will last a lifetime. Every titanium model affords a rock-solid, stable action and exudes confidence in every word it writes.
Refills
The Ko-Axis™ Rail Pen includes a Monteverde D1/Multipen refill, which we think is the best refill on the planet. This medium point, black ink refill is the perfect way to experience everything the Ko-Axis™ has to offer. It features Soft Roll ink technology which is a low viscosity ink for the smoothest writing experience, with a high quality nickel silver tube and a Swiss tip.
However, any D1 style refill will work in the Ko-Axis™, including but not limited to the following:
- Schmidt 635 Mini D1
- Lamy Mini Ballpoint Refill M21
- Kaweco D1
- Monteverde D1/Multipen
- Parker D1
- Zebra Sharbo X Gel Ink Multi Pen/D1
- Zebra ESB-0.7 Emulsion Ink Ballpoint Pen Refill - D1
- Ohto R-4C7NP Needle-Point D1
- Rotring D1 Multi Pen