The handy water holder & brush all in one.A Derwent Waterbrush is perfect for taking out into the field; no need for water pots & endless traditional brushes! They are portable, easy to use & great alongside any of our water-soluble pencils & sticks. They house water in the barrel of the brush which is supplied to the fibre tip via a valve, giving a constant flow of water when the brush meets paper. For wet on wet techniques just add slight pressure to the barrel & to clean it simply apply pressure to the barrel & the dirty water will work its way out of the brush. The Waterbrushes have a patented valve that stops water from leaking & potentially ruining artwork. The medium Waterbrush with its larger brush head is perfect for broader strokes.