Vivid colour for a huge range of uses! The water-based pigment ink in the Uni POSCA Markers is lightfast, waterproof and writes on virtually any surface. It won't feather and won't bleed through paper, unlike alcohol-based markers. What's more, the ink is opaque, and if allowed to dry after application, different POSCA ink will completely cover the previous colour. PC-1MR - ULTRA-FINE CALIBRE - 0.7 mm Posca's PC-1MR ultra-fine tip has the same qualities as a paint marker.in a pen. It is designed for professionals and beginners requiring an extra-fine and consistent line in a wide selection of colours. Posca's extra-fine calibre tip is ideal for professionals such as graphic designers to produce technical drawings and rough sketches. Artists will appreciate Posca for the ideal finish, defined details and outlines. Posca is also ideal for creative crafts hobbyists for scrapbooking or making greeting cards. Posca Markers are available in up to 33 different colours in 4 different tip sizes and finishes, so there is sure to be a pen for you.