INKZALL™ Markers are designed for tough jobs, staying sharp without mushrooming or pushing back under pressure. The acrylic nib writes on rough surfaces like OSB and concrete, and keeps working even after 72+ hours with the cap off. Suitable for concrete, wood, metal, plywood, OSB, and plastic—even on wet, oily, dusty, or rusty surfaces. Quick-dry ink minimizes smearing, while the thin body reaches tight spots. Features include a helmet clip, one-hand easy-open cap, and anti-roll design for convenience on the job site.