The set contains of Pigma Micron 01 (0.25 mm), Pigma Micron 05 (0.45 mm), Pigma Micron 10 (0.60 mm) and Pigma Brush - all in cool gray. With these buildable grays you can add shading, depth, visual accents and layering effects to illustrations, drawings, bullet journal spreads and so much more. Pigma Micron pens are waterproof and permanent fineliners that are loyally used by designers, scientists, archivers, manga artists, cartoonists, illustrators and hobbyists. It is the recommended pen for Zentangle. The fine nib makes this pen ideal for creating both technical and artistic drawings. The unique Sakura Pigma™ ink will not bleed through paper, is permanent, waterproof, fade resistant, quick drying and pH-neutral.