Pilot Ball liquid ink refills fit the ball rat retractable rolling ball pens These ink refills contain smooth writing smear-proof liquid ink and are available in a 2-pack with extra fine (0 5mm) points for your favorite Pilot ball ink pens The refills feature a liquid ink feed system that assures smooth skip-free and consistent writing They are even safe for airplane use The unique liquid ink formula maintains consistent flowing strokes - no smearing or blotting