Promarkers was the first markers I bought, they have two different nibs and can´t be refilled. I use them for coloring larger areas and smoothen the borders between different shapes. Most of the time I use the trias to "draw" with, to get the fine lines, and then I go over the areas that I want to smoothen up with one marker ( see top image), satin is my favourite. In my drawings there are very little clean white paper left, and what can be taken for white is almost never white. Therefor most of my promarkers are in neutral colors.