FEATURES: Stays sharp, doesn't mushroom or push back under pressure. Acrylic nib ideal for rough surfaces such as OSB and concrete. Marker continues to write after 72+ hours of cap off time. For use on concrete, wood, metal, plywood, OSB, plastic. Can be used on wet, oily, dusty, rusty, with debris surfaces. Quick dry time – reduced smearing markings on PVC, metal surfaces. Thin body for use in restricted areas. Helmet clip – can be clipped to the construction site cap, trousers, overalls. Easy open cap for one hand operation. Anti-Roll design - won't roll off surfaces.