Our DirectGlow brand UV blacklight reactive invisible ink markers use high quality semi permanent invisible ink. Perfect for identification marking, secret messages, and other stealthy security uses. Glows an incredibly bright blue/red in blacklight! Perfect for metal, plastics, paper or any porous surface. Safe for skin and body as well. Totally invisible, won't wash off easily, and is only visible under blacklight. These markers have a large body and broad tip. Great for shading in large areas and making larger marks than our standard fine tip markers. They also have 2x the amount of ink inside! These is the markers you want for semi permanent, invisible marking. These markers can be used for: Event Tickets, Industrial Coding, Security Printing, Coupons, Raffle Tickets, Inventory Control, Advertising, and more! Can also be used on: Aluminum, ABS, Acrylic, Rubber, Cellulose, Acetate, Formica, Nylon, Polystyrene, and Polyethylene. Ink is non-toxic, fast-drying and non-transferable.