The Uni Posca markers are water-based gouache paint markers. They are hard to find in Germany but seem to be very popular abroad. The only available sizes of these markers in Germany are the fine ones (3mm and 5mm). I first spotted the bold ones on a trip to Paris in the early nineties, until then this kind of water-based markers, like the Artline Poster Markers, were unknown to me (well, the Poster Markers were sold in Germany in the 1980s, however, the Poscas weren´t).
The markers are available in a huge color range and are very suitable for artwork since they are opaque like and therefore covering also on darker surfaces. Good quality markers!
The smaller 8mm orange Uni Posca and the 15mm yellow one I bought in Paris. Therefore both are labeled in French. The black 15mm is only a few years old, like the other 8mm Poscas. I bought them in Spain.