paint markers have a rugged crush resistant metal barrel and a pump valve action paint flow control to ensure consistent output. The marker has an acrylic fibre bullet tip which writes a 2.3mm line .They contain a solvent based ink which is xylene free. paint markers are highly water and fade resistant and are ideal for both indoor and outdoor use. They are fast drying and suitable for use on metal, glass, plastics not EPS, ceramics, wood, rubber and laminates. Purchasing each unit.