Prismacolor's remarkable, double-ended, 4-in-1 design is incredibly versatile. Broad-tip end allows you to draw wide, medium and thin lines with ease. Fine-tip end, ideal for details, has been improved to allow more color laydown in one stroke. Rich colors offer juicy, smooth flow. Low-odor, dye-based alcohol ink is permanent, non-bleeding and non-feathering on most surfaces. Works on a variety of papers including watercolor paper and even smooth vellum. Indigo blue. AP Seal, non-toxic.