These three water brushes are valuable (if not to forget to fill their tank) as they are a very useful tool to diversify sketches. A Recipe: Make a sketch (landscape, character ...) with a non-permanent marker and cross out strongly the dark areas. Sweep brush to wet your hair and scratched area become very dark. So, your sketch will have more strength. It is also possible directly from a China-ink dilution water into the reservoir to draw directly brush ... In short, it's a great tool and I am thrilled with this purchase that I recommend to all fans.