The Kaweco M Yellow 6-piece refill box provides a bright, transparent shade for decorative effects and clear writing. It contains 6 standard short cartridges filled with bright, water-soluble yellow ink, ensuring continuous and unclogged nib feeding. It is compatible with all Kaweco nib pens and instruments with the European universal refill system. The vibrancy of the yellow is excellent for highlighting techniques, experimental calligraphy, planner titles, and note-taking.