Features & details Features 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 kids Invisible 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!