Pigma Light Cool Gray & Cool Gray Micron Brush 8 Piece Set features archival-quality ink for use in acid-free environments. They are chemically stable, waterproof, fade-resistant and produce no smears, feathers or bleed-through on most papers. Package includes eight pens in two shades of gray in sizes 01 (.25mm), 05 (.45mm), 10 (.60mm) and BR.