The writing point is a tiny ball, usually 0.5 or 0.7 mm in diameter, that transfers the ink from the reservoir onto the paper as the pen moves.
The "liquid-ink" type rollerball pens were introduced in 1963 by the Japanese company Ohto.
[2][3] The gel-ink type rollerball pens were patented in 1982 by Sakura Color Products.
[7] The Ohto Model CB-10F Ceramic Roller Ball Pen was used at the 1990 Economic Summit of Industrialized Nations.
[8] The Supreme Leader of Iran has also frequently been observed writing with a Uni Ball UB-100 rollerball pen.