Cartridge ink for "board marker (sold separately) with dark strokes that can be seen clearly even from a distance. [Features] This is a dedicated cartridge ink for "board marker (sold separately) with dark strokes that allow you to see clearly even from a distance. It allows you to continue writing steady from start to start using it until the ink runs out, so you can always write dark and crisp, without leaving any marks on the way. You can see how much ink is left. Compatible with all types: medium / bold, log / chisel / extra thick core.