These dual brush pens have a versatile and flexible nylon fiber brush tip on one end that creates medium or bold strokes by simply changing brush pressure. The fine tip on the other end is for smooth straight lines or writing. The water based ink is blendable, odorless and non-bleeding. Acid free and non- toxic. Perfect for fine art techniques. Conforms to ASTM D4236. 10/Pkg. Tombow DBP10-56167.