Hide the Secret Message You Write: This magical invisible ink pen allows you to write down your secret information and hide it,Once Write down your secret message with this invisible ink pen,Wait a moment,The words or patterns you write will disappear,You can turn on the light on the pen's cover and reveal the secret of the secret message. INVISIBLE INK PEN WITH UV LIGHT: Harmless and tasteless ink, healthy toy for your kids Smooth and colorful disappearing inks on t-shirts, paper, skin and any surface Permanent but washable With 7 in the bag, you can easily host a kid's birthday party favors stocking stuffer, treasure hunt,escape room,or classroom activity complete with invisible ink clues Great Gift for Fun Party Favors: This invisible Spy Pen comes in a pack of 7 and can write your secret in the sticky note. Different colors make the activity more exciting and entertaining. Parents can buy it for their kids party at home. Kids love using this kind of pen to keep their secret and play detective spy games. Batteries included and installed.they each had a pull tab to save battery life. Pens will be available in different colors to keep the activity exciting.Be careful with small items: children over 3 years.