Nylon brush tip pen filled with water-based (dye) ink. 12 vibrant colours to choose from. Create beautiful, vivid, translucent, watercolour effects. Valve-activated for smooth flow, without leaking. Replaceable cartridges available. Convenient, portable alternative to traditional brushes. Pentel Colour Brush Pens offer artists beautifully vibrant dye-based ink in a brush pen with nylon bristles. The ink blends between colours and can be washed with water for watercolour-like effects. We recommend using these brush pens on smooth watercolour paper or bristol board, or a watercolour sketchbook and waterbrush for expressive and colourful artwork whilst you are out in the field. Product Details: Nylon brush tip pen filled with water-based ink. 18 vibrant colours to choose from. Create beautiful, vivid, translucent, watercolour effects. Valve-activated for smooth flow, without leaking. Synthetic fibre tip retains its shape. Convenient, portable alternative to traditional brushes. Refillable cartridges.