These dual brush pens have a versatile and flexible nylon fiber brush tip on 1 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 resilient nylon brush retains its point, stroke after stroke. The ink is water-based and blendable: use 2 colors together, or use the colorless blender pen. The pen tips self-clean after blending so there is no messy clean-up! Use these pens for coloring, rubber stamping, hand-lettering, doodling, journaling, and more. Perfect for fine art techniques. The ink is acid-free, non-toxic, odorless, and non-bleeding. Each package contains 10 pens (9 colored, 1 colorless). Available in a variety of color schemes, each sold separately. Conforms to ASTM D 4236.