The 6-bristle Filbert brush is most often used for seascapes, but can also be used for tree trunks and other small detail work. The Bob Ross Landscape Brushes are special brushes made from a mixture of natural and synthetic bristles, shaped to Bob's very precise specifications for the Bob Ross Wet-on-Wet Techniqueëå. Remember that ordinary brushes are not the same and cannot achieve the same beautiful effects as these.