Thank you for looking! This is a pen that glows under blacklight. [Product Features] • Invisible Ink: It's transparent immediately after writing and invisible. • Decipher with Special Light: When you shine the UV light (blacklight) attached to the end of the pen (sac tip), the written text will vividly appear. • Set of 5 Colors: We will deliver 5 pens from the colors blue, red, orange, green, purple, and pink. (⚠︎ These are not the ink colors. All inks are transparent and glow in fluorescent colors under UV light.) [How to Use] 1. Write letters or draw pictures on paper, etc., with the pen. 2. Press the switch area at the top of the pen (light part). • Be sure to remove the white part (insulating sheet) circled in the photo before use. Removing this will allow the light to turn on. 3. Shine the light on the area where you wrote, and your secret message will appear!