Derwent : Aqua brush water brush : Medium tip. The Derwent Waterbrush is perfect for taking out into the field; no need for water pots and endless traditional brushes! They are portable, easy to use and great alongside any water-soluble pencils and sticks.
The brushes 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 and to clean it simply apply pressure to the barrel and the dirty water will work its way out of the brush.
The Waterbrushes have a patented valve that stops water from leaking and potentially ruining artwork.