MILWAUKEE PROFESSIONAL TOOLS PERMANENT LIQUID PAINT MARKERS Liquid outlet via valve. Acrylic tip for the most demanding working conditions: surface temperature from -10° to +145. Marking on dark surfaces where traditional markers are not easily visible. Can be used on rough, dusty and greasy surfaces. For use on concrete, black pipes, aluminium, PVC, steel & stainless steel, rubber and tyres. drying time 10 seconds. Water and UV resistant marking. Permanent markers. Markings last up to 6 months. Metal body for maximum durability. Paint without Xylene. IMPORTANT: Shake the marker with the cap inserted. Remove the cap and carefully squeeze the tip towards the surface to be marked, waiting for the liquid to flow into the tip.
These are brilliant for marking out or even for calculating numbers on materials on anything. I would definitely recommend to anyone as they are so easy to use and can just be seen at any time