Tombow Dual Brush Pens feature two tips on each pen - flexible brush & fine tip in one. The ultra fine nylon tip creates clean, crisp lines for sketching & detail work. The flexible nylon brush creates fine, medium & bold strokes simply by changing the pressure applied. The high quality resilient nylon tips will hold their shape stroke after stroke to create consistent lines for borders, graphics, writing, & drawings. . They are non-bleeding, odorless, non-toxic, acid free & waterbased.