Sharpie Professional Marker contains ink that is permanent on most hard-to-mark surfaces such as wet and oily surfaces, sandpaper, concrete, brick, glass, metal, plastic, wood, sporting equipment and much more. The strong Sharpie Professional chisel tip lasts 50 percent longer than standard chisel tips. The rubberized barrel and cap design make the cap easy to remove even when wearing gloves. Quick-drying is certified AP nontoxic.