Pigmented India ink that is both acid-free and archival (PH neutral) Smudgeproof and waterproof when dry. The ink contains the highest quality pigments for unsurpassed lightfastness. Lightfastness rating and color name noted on barrel of each pen. Artist brush pens are ideal for graphic artists, illustrators, designers and architects. Perfect for sketching, journals, cartooning, fine-ink drawing, scrapbooking and rubber-stamping. The set of four contains the following: S = 0.3 mm, F = 0.5 mm, M = 0.7 mm, B = brush tip. The set of eight contains XS = 0.1 mm, S = 0.3 mm, F = 0.5 mm, M = 0.7 mm, B = brush tip, 1.5 = bullet nib 1.5 mm, SB = soft brush tip, SC = soft chisel tip.