Invisible Ink Pen, Spy Pen with 9 PCS Mini UV LED Keychain Flashlight, Disappearing Ink Magic Pen with Black Light Markers for Secret Notes, Fit for Christmas Halloween Holiday Gifts (9 PCS)

Works great! Very vibrant colors under the black light.

This thing saved me so much money! I sell expensive stuff and I mark them with these when I send them out. So there's no question as to if it's mine when/if they try and send it back. Thousands saved!

I will use this for an escape room. One of the lights did not work.

I only used 1 pen for all 300 invitations. They were easy to use and perfect!

the kids will enjoy writing secret letters to each other. Im sending my bf a love letter in the mail, but leaving the light out of the envelope. So, when I arrive on his doorstep with the light, he'll then have to decode the message, as well. I will also write messages on the bathroom floor, wall, the refrigerator and headboard there, so he can find each message as he finds clues hidden in his sock drawer, butter dish, keychain, instructing him to solve a clue to find the next message... etc etc... fun!

Exactly as advertised, I have no qualms with this.

Pens are good but the lights need improvement

I used this for an escape room puzzle. The pens were perfect. You could not see any marking once it dried. I would have given 5 stars but the two out of the three little black lights died very quickly. Great that there were three in the package.