Rollerballs That Take Fountain Pen Ink: Three Pens Compared

Introduction

Fountain pen fans tend to prefer nibs to any other writing mode, but there are moments when a rollerball is genuinely more practical. The catch is that standard rollerball ink options are limited. Rollerballs that take fountain pen ink solve that: they use a converter, so any bottle ink is on the table, and many of them are surprisingly comfortable writers.

This comparison brings three converters-in-a-rollerball options side by side: the Monteverde One Touch Engage, the TAG Submarine Collection rollerball, and the Inventery Pocket Pen 2.0. Each takes a different approach, and each has clear strengths and trade-offs.

Monteverde One Touch Engage

The Monteverde One Touch Engage is the only pen here with a click mechanism, which means true one-handed operation. Inside you will find a spring for the mechanism, a converter, and a cartridge adapter, so you can also run it on standard international cartridges if you prefer. The carbon fiber finish is large and light, with a slight top heaviness.

There are trade-offs to consider. The tip is exposed, so the pen has no cap to seal the ink; in theory fabric catching the tip could pull ink out, though the design is a rollerball rather than a fountain pen nib, so drying out has not been a major issue in practice. The other drawback is size: it is a very large pen, and writers with smaller hands may find the grip angle awkward unless they hold it a little higher up the barrel. On the positive side, pressing down slightly on the click mechanism pushes the ball in harder and delivers a visibly wetter, more saturated line.

Street pricing has been around $76, but stock has been inconsistent across many shops, so availability may take some hunting. If you need a retractable rollerball with fountain pen ink freedom, it is a genuinely cool option, just one that suits larger hands best.

TAG Submarine Collection Rollerball

The TAG Submarine Collection rollerball launched on Kickstarter and is made in Taiwan, with a lot of brass in the construction. That makes it a very solid pen, and the design has real character: a cap that does not post, grooves on the section that add comfort, and a turbine-shaped finial at the end that doubles as a piston turning knob. The converter screws in place inside the barrel, and ink can be drawn from a bottle.

This was the most comfortable writer of the group in terms of feel, with a more refined shape than the oversized click pen and excellent section comfort. You can also press lightly on the tip for a wetter line. A few cautions: the brass makes it heavier than some writers will enjoy, and the turbine finial can be fiddled with accidentally, which expels a drop of ink from the tip. Filling by dunking the whole barrel into a bottle also risks ink seeping from the seams, so careful filling or cartridge use is worth considering for settings where ink-stained hands are unacceptable.

These launched at $100 US, making them more expensive than the click pen. If you like the look of solid brass and want a well-designed, comfortable rollerball, this one earns its place.

Inventery Pocket Pen 2.0

The Inventery Pocket Pen 2.0 is the most versatile of the three. It is actually a fountain pen that comes with a Schmidt nib insert, and the rollerball insert is included, so you get two writing modes in one purchase. The original version was made in China; version 2.0 is made entirely in the US, with minor changes to the clip and finial. Finishes include brass, stainless steel, and black anodized aluminum, so you can choose a lighter material if brass feels too heavy.

There is also a clever extender design. Remove the converter, unscrew the middle barrel section, and the cap threads onto the back for a true pocket pen form. The trade-off is that the converter no longer fits in pocket mode, limiting you to standard international short cartridges, which matters for your ink selection. In extended mode, the pen is pleasant unposted; posting the cap makes it long and slightly top heavy with the brass. The section has a little sharpness near the grip, though there is enough surface to hold comfortably.

Pricing is $189 US with the extender and $140 without, making it the most expensive here, but you are also getting a fountain pen nib in the deal. Among the three, this one writes the smoothest, with a tip that feels a touch wider, closer to a medium, while the other two feel more like fines.

Which One Should You Pick?

This is a subjective call, but the ranking is fairly clear for these preferences. The Inventery Pocket Pen 2.0 takes the top spot: it is the best writer, the smoothest mechanism, and the two-in-one nib-plus-rollerball format plus the optional pocket conversion deliver real value despite the highest price. The TAG Submarine Collection rollerball is the strong second choice, a very comfortable and well-designed brass pen that simply demands care around the turbine finial and ink filling.

The Monteverde One Touch Engage finishes third. It is a handsome, fun pen with a genuinely useful click mechanism, but the sheer size makes it a poor match for smaller hands, and the uncapped exposed tip is a fair trade-off to weigh.

Conclusion

Rollerballs that take fountain pen ink are a fun, practical middle ground: full access to your bottle inks with rollerball convenience. If you want maximum versatility and the smoothest writer, the Inventery Pocket Pen 2.0 is the pick. If solid brass and design character appeal to you, the TAG Submarine Collection rollerball is excellent. And if one-handed operation matters most and you like big pens, the Monteverde One Touch Engage is worth tracking down.