The filamented brush tip makes all the difference for creating a dynamic range of delicate fine lines to bold, expressive strokes. It mimics a paintbrush but has all the conveniences and control of a marker. Activate the brush by removing the yellow ring between the nib and barrel, and the sides of the barrel are squeezed to get the ink flowing. Once activated ink flows smoothly without starving or over feeding. Replacement ink cartridges are available to extend the life of your pen.