The 6-pack of Kaweco M green fountain pen refills ensures a vibrant, natural green tone with excellent writing fluidity. It contains 6 short, internationally standard cartridges filled with high-quality soluble liquid ink that provides a smooth, clean line. They adapt immediately to Kaweco Sport pens and models with universal cartridge systems. The intensity of the leaf green tone is fantastic for highlighting important ideas, study notes, ink drawings, and colorful, informal correspondence.