These dual brush pens have a versatileand 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 colorless blender Brush Pens are ideal for artists and crafters. The water-based ink is blendable and the resilient nylon brush retains it's point stroke after stroke. The tips self-clean after blending.The water based ink is blendable, odorless and non-bleeding. Acid free and non-toxic. Perfect for fine art techniques. This package contains ten pens. Available in a variety of color combinations: each sold separately. Conforms to ASTM D4236.