In General, we refer to this type of writing is called "needle". Its key differences with the bullet pen is that it is formed by the non-cutting machining. Into before writing, it is a complete tube, front end of the tube by precision instruments from 3 directions 3 pits, forming ball Bowl; but behind the thin tubes formed a triangle of the oil tank. Ink by the oil tank and then ball rolling out of the ink, through the writing process. Needle type suitable for producing fine writing, for example, 0.30, 0.25 and so on.