Dual brush pens have a versatile, flexible nylon fiber brush tip on one end and a fine tip on the other end. The resilient nylon brush retains its point. Water-based, non-bleeding ink is blendable. Set includes 10 grayscale pens: cool gray in 1, 3, 5, 6, 7 and 10; warm gray in 1 and 2; lamp black and black. Acid-free. AP Seal, non-toxic.