Paint "en plein air" with these portable, refillable Derwent plastic barrel water brushes. There s no water pot required and no spills to worry about, plus they re easy to clean. The small (#1) tip has a fine point for sharp, detailed lines. The medium (#2) tip is best for broad lines. The innovative chisel (#3) tip is best for sharp, fine lines and broad strokes. Water is supplied to the synthetic fiber tip via a leak proof valve.