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.
