The rollerball uses water-based ink and writes softer and smoother than a standard ballpoint pen.
A gel pen (e.g. Centrum Nice 0.7mm) is similar, but the ink is thicker and has brighter colors.
Yes. Pentel Energel offers colors such as turquoise, pink, purple, light green, as well as metallic and pastel rollerballs from the Hybrid, Dual Metallic and Milky series.
The Pentel Dual Metallic and Hybrid Milky/Pastel series offer dual color, pearlescent effect and thick ink – ideal for drawing on dark paper and creative projects.