Work through the toughest conditions with these Marks A Lot UltraDuty Permanent Markers. Designed for moments when traditional permanent markers aren't strong enough, industrial-grade markers are ideal for workshops, warehouses & construction sites. They work on metal pipes. Industrial markers are also excellent for writing on plastic bins, wood pallets & concrete walls. Sturdy tip also writes clearly on wet, dusty, oily & abrasive surfaces without clogging. Flat & angled, 0.5mm chisel tip also allows varying line widths so that you can go from thin to bold on the spot. Great as outdoor permanent marking, the specially engineered, black marker ink is also resistant to water, abrasion & smearing while still remaining bold & visible. Industrial ink won't dry out when the cap is left off for up to 72 hours. Useful, built-in clip keeps the marker from rolling off surfaces & offers a way to loop into lanyards for extra security. Colors include black & red.