方型漸變到圓型、大漸變到小，直覺的設計將筆頭特性完美地告知，並搭配幾何圖形，將雙向筆頭的資訊最精簡化。

Square to round, big to small, the intuitive design perfectly informs the pen characteristics, and with geometric figures, the information of the two-way pen is most simplified.