1.8 – 2.5mm bullet tip makes this pen a great all-rounder, good for hand lettering and bold, robust drawings Not suitable for porous surfaces Perfect for pub, cafe© and restaurant signs Rain-resistant – so your message will hold up outdoors – but the ink is water-based so if you want to remove it simply wipe away with a damp cloth, or a little mild detergent if stubborn The uni Chalk Marker writes on and wipes off making it the perfect tool for sign writing on non-porous surfaces such as chalkboards and glass