I have these markers on it already several months. I use them in learning - where I also use quite a lot of mathematical symbols. The typeface is really nice, you can write with the markers on the whiteboard as a filler in paper; especially fine lines are possible.
In my view, the blue and the black marker but unusable. The reason is that you have to exert a lot of power to the wiper to abzubekommen the color and you can entirely avoid residues only when wet wipes. If the font is still fresh so it is blurred. A quick wipe is therefore hardly possible. Meanwhile, I have of the black pen even residues on the whiteboard that can be wet themselves not completely disappear (but certainly with a suitable solvent).
The font of red and green pins wipe away much easier. I write therefore only with the red pen and have succeeded in this way the red pen in learning within a week empty attribute, ie, at least so empty that I have no "whopping" line more. This is my decision to short life - even if the pen is refillable.
