Our Opticz 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 and yellow 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. The large markers have a large body and wide tip. Great for shading in large areas and making larger marks. Our standard fine tip markers have a very fine point allowing for precision application and fine detail. You also get a quality 12 LED UV flashlight that will illuminate and reveal the ink. Flashlight runs on 3 AAA batteries (not included). It has an aluminum build, is water resistant and will last for years if well cared for. 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. Fine tip for precision application. Ink is non-toxic, fast-drying and non-transferable.Prolonged exposure to sun light or continuous high powered UV exposure may cause fading over time.