Quite simply, wow!the medium tip Pentel water brush is an artist's brush that houses water in a barrel in the brush handle. The water is supplied to the fibre brush tip via a valve, giving a constant flow of water when the brush meets a porous surface. For wet on wet techniques just add slight pressure to the barrel and to clean the brush simply apply pressure to the barrel and the dirty water will work its way out of the fibre tips. Great for both outdoor and indoor use, the water brush is ideal for any water-based medium.Get creative with the Pentel water brush - you'll love it!