【Interesting Spy Activities For Kids】Invisible pens with built-in purple lights. Batteries included and installed. Please BE CAREFUL with small items: Children above 3 years..【Write Your Secret Message】These invisible ink pen with purple light will write your secret message. Once your secret message is written with this spy pens, wait a few seconds shine the light from the cover of the pen and REVEAL MYSTERY OF THE SECRET MESSAGE. Besides, This design with the built-in LED on every pen. This makes every individual marker a complete system for creating and reading invisible messages..【Safety for kids】Safety and tasteless ink, the ink is a food-grade pigment, healthy for your kids! Smooth disappearing inks on t-shirts, paper, skin and any surface! These washable invisible pen now come in an improved Ultra-Clean formula that washes easily from skin, clothing, and walls.! With 24 or 32 each package, you can easily host a kid's birthday party,treasure hunt,escape room,or classroom activity complete with invisible ink clues!.【Purple Light Last Long And Ink Will Not Run Out Quickly】The battery of our invisible disappearing ink pen is button cell, it is replaceable, once the light don’t work ,you can contact us for a new button cell.Besides,Ink of this spy pen Will not run out quickly if you use it in normal condition..【Great Gift For Girls Boys Fun Party Favors】 Assorted colors to make the activity like Wedding RSVP Black Light Party more exciting and fun; Parents could buy it for their kid’s party at home; These would be a treat for kids who like secret spy games, carnival games, for those who like passing secret notes or leaving clues that only certain people can see.Teachers can buy it for students for treasure hunt, or classroom activity.