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.spy gear for kidsInvisible Ink Pens with UV Light: Harmless and tasteless ink, healthy toy for your kids! Smooth and colorful disappearing inks on t-shirts, paper! Permanent but washable! you can easily host a kid's birthday party favors stocking stuffer, treasure hunt,escape room,Valentines Day Gifts or classroom activity complete with invisible ink clues!Great Gift for Fun Party Favors: This invisible Spy Pen can write your secret in the sticky note.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. Schools, teachers can buy it for students for a school activity. Add it for any surprise gift bag or as a kids stocking stuffers.Package includes: 7 PCS invisible ink pens with built-in UV lights. Batteries included and installed.they each had a pull tab to save battery life.Be careful with small items: children over 3 years.