The Aquastroke Brush Pen is an innovative way to paint with water-soluble mediums either on-the-go or in a studio! Aquastroke allows you to add water without carrying a separate water supply. Just fill the barrel with water and you're ready to go! Because Aquastroke pens have their own water basin, artists need not worry about spills or messes-- making these pens are perfect for plein air! Aquastroke Brush Pens are made with high quality, white nylon brush tips.