These uni prockey permanent markers are a great marking option as you can use them on almost any surface. The odourless, water-based ink will not bleed through thin or porous paper so they can be used in a number of environments. These markers have a 5.7 Mm chisel nib which allows you to write both thin and thick lines. They are a great option to always have handy as they can write on almost any surface. The water-based ink is both odourless and permanent. The markers have an easy to hold, thick round barrel. The ink will not bleed through thin or porous paper.