The Tombow Water Brush is an ideal companion for the Tombow Dual Brush Pens. It makes it easy to blend water-based markers, watercolor paint, pencils or crayons with the soft, flexible brush tip. You can fill it with water to blend, or add ink or dye for color applications. Gently squeeze the barrel to apply. Use the Small and Medium Water Brush for fine details, and the Flat Brush for broader coverage. Available in Small, Medium, and Flat brush tips. Fills up to 5.5ml.