Spy Pen: The ink is invisible after you write with it, unless you turn on the cap's blacklight to reveal the secret message perfectly. Invisible Ink Pen: Harmless and tasteless ink, a healthy toy for your children. Smooth and colorful disappearing ink works on t-shirts, paper, skin, and any surface. Permanent yet washable. With 14 pens in the bag, you can easily host a child's birthday party, stock up on stocking stuffers, create a treasure hunt, design an escape room, or plan a classroom activity complete with invisible ink clues. Exciting Spy Activities for Kids: Kids will love these pens! They love using this type of pen to keep their secrets and play detective spy games. The invisible pen provides a fantastic amount of fun activities, from surprising birthday parties to revealing a top-secret message to their parents or grandparents. Great Gift for Fun Party Favors: Perfect for wedding invitations; makes a fun party favor; provides a fantastic amount of fun applications. Birthday gifts, Halloween gifts, Christmas gifts for kids and friends. Kids love using this type of pen to keep their secret and play detective spy games. Schools and teachers can buy it for students for a school activity. Add it to a surprise bag or as a stocking stuffer. Package Includes: 14 invisible magic pens with built-in UV lights. Batteries are included and installed. Please be careful with small objects: suitable for children over 3 years old.