The Milwaukee Hand Tools INKZALL™ Highlighters have a durable tip that stays sharp longer, with no smearing or bleed through. They use non-toxic ink, ASTM D 4236 certified. Ideal for architectural drawings, labels, office paper, etc. The highlighter body has an anti-roll design, so it won't roll off surfaces. There is a handy helmet clip so it can be clipped to the construction site cap, trousers overalls etc. and also features a lanyard hole.