Pilot Acroball Knock Ballpoint Pen, 1.0mm, Black(BAB-15M-BB), 6 pens per Pack (Japan Import) [Komainu-Dou Original Package] Ink color: Black The ball diameter: 1.0mm. Medium Type. Smooth oil-based ink "Acro Ink" Rubber grip to be able to grasp well 6 pens per Pack