This is a Uni Style Fit pen refill inks of Jet Stream ink. Often oil based ink does not write as smooth as gel ink , but Uni's Jet Stream oil based ink writes very smooth. Colors are available in 3 colors. Style Fit offers you to choose your favorite body and mix and choose your favorite colors to create your own multi-pen combination. You need a pen body to use the refills.
You might wonder what the difference between Jet Stream ink (oil based ink) and Signo (gel ink). Well, since both write smooth, there is no super big difference between them, but the advantage of oil based ink is that the ink is not used up as fast as gel ink does. Also oil based ink writes more crisp. The advantage of gel ink is that it can have wide variety of colors compared to oil based ink, and it write smooth. Personally, we like using Jet Stream in color of black, and for other colors we like using gel ink.
We like using black Jet Stream ink for our Traveler's Notebook and other regular notebooks, and for Hobonichi or Tomoe River paper, we recommend gel ink pens.
* Pen Width: 0.5mm, 0.7mm, 1.0mm
* Colors: Black, Red, Blue
* More Uni Style Fit series HERE