For Pilot brand pens only (Kakuno, Prera & Capless).
A small metal ball inside the converter insures a consistent ink flow and reduces air bubbles.
In 1915, Ryōsuke Namiki, a mechanical engineer and professor at the University of Marine Science and Technology in Tokyo, quit his job and, together with his colleague Masao Wada, founded a small factory to manufacture gold nibs for fountain pens, which they named Namiki Manufacturing Company. Three years later, Pilot was born. With its wide range of writing instruments, Pilot has quickly become one of the best and most popular pen companies on the market.