Rollerball refill cartridge with a ball diameter of 0.5 mm (equivalent to a line width of approximately 0.3 mm).

With these ink roller refills, all Tombow ink rollers become a long-term companion. Depending on personal preference, the rollerballs can be refilled in three different ball diameters and three different colors: blue, red, and black. The high-quality pigment ink is additionally protected from drying out by a plastic ball that must be removed before first use.