They will think they are secret agents with these pens. Fun for sure and they can play with these all day long! multiple purposes you can use these invisible pens on many different things and create a lot of fun, such as encrypting wedding invitations, identifying your personal valuables or even using the UV light to check dollar bills.
Built-in UV light it is a great idea to have the UV light installed in the cap so you do not need to buy a spare light.
It comes with everything in it so your children and their friends can instantly play with these and see the secret messages they write.

• Funny pens with harmless and flavorless ink, you can write everywhere: T-shirts, paper, skin and any surface! Healthy toys for your kids and environmental pens !
• invisible ink pen will write your secret message: when your message is written by the pens, nothing you will see , but you can see message clearly with light from the top of the pen .that's the secret message pen.
• Material: abs
• Size: 13.3cm/5.24"
• Color: blue, green, purple, pink, yellow, black, red (Color May Vary)