Features flexible nylon fiber brush tip on one end and a fine tip on the other end Brush pressure can be used to create medium or bold strokes Ink is water-based blendable, odorless and non-bleeding Acid free and non-toxic There is a versatile, 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 waterbased ink is blendable, odorless and non-bleeding. Acid free and non-toxic.