Easy marking of hard-to-reach points such as for marking drilling holes. Ideal for marking deep holes and inspection. Quick drying time - reduces smudges during marking. Writes without drying for up to 72 hours without a cap. Strong, permanent, yet non-toxic ink. Waterproof for permanent writing on almost all surfaces, e.g., cardboard, metal, glass, concrete, cement, wood, plywood, OSB, plastic, and more. The built-in cap with a pocket clip allows for easy carrying and storage. An essential accessory in every handyman's toolbox.