The uni 580 marker contains permanent ink and can be used to write on almost surface. The ink is alcohol-based, waterproof and designed to dry quickly for smudge-proof results. Each marker has a 5 mm chisel tip. It's suitable for use on paper, cardboard, wood, plastic and more. The ink is alcohol-based for permanent results. The ink is xylene-free for added peace of mind. There are 4 markers in this pack, in assorted colours.