The ZIG Watercolour System Brush H20 range is perfect for any artist who wishes to paint anywhere at anytime. All you need to do is fill the barrel with water and away you go. The ZIG Watercolour System Brush H20 pens have a retractable valve in them so you have complete control of how much fluid you release by gently squeezing the barrel. Alternatively you can fill with most waterbased media such as dyes and inks (that are rewettable).