Invisible Ink Pen Permanent InkThis UV Pen/Marker uses high quality permanent invisible ink that is invisible when dry and becomes visible under ultraviolet light (blacklight). Perfect for identification marking, wall decoration, and other stealthy security uses. Glows an incredible bright blue. Perfect for metal, glass, plastics, etc. Totally invisible, won't wash off, and is only visible under blacklight. Solvent based and not recommended for use on the skin. This is the pen you want for permanent invisible marking to protect your valuables.