Pitt Artist Pens offer odorless, permanent and waterproof inks that will not bleed through paper. The pigmented India inks are lightfast, acid-free and pH Neutral. The medium tip pens are 0.7mm and are used daily by artists worldwide for illustrations, fashion design, life drawings, portraits, sequential art and canvas paintings. They work beautifully on all types of papers and canvas, permanent on porous surfaces. Ideal for sketches and studies in ink. Store horizontally when not in use.