Based on the writing technic the roller ball is located between fountain pen and ball pen. It is trying to combine the positive attributes of both writing instruments in one. The roller ball adapts the flexibility and easy usability of a ball pen. Out of the fountain pen it imitates the smoothness of writing and the comfort by using ink as writing medium. The ink-mines can be exchanged when they are empty, in the same way as you would do with a ball pen. Depending on the producer you have the opportunity to choose between different line widths of the mine.