Write your secret message: this invisible ink pen will write your secret message. Once your secret message is written with this invisible ink pen wait a few seconds shine the light from the cover of the pen and reveal mystery of the secret message. Exciting spy activities for kids: kids will love these spy pens. Kids love using this kind of pen to keep their secret and play detective spy games. Invisible pen brings you an amazing variety of fun activities. Material: plastic. Color: show as pictures. Size: 13.4 * 1.5cm There might be a bit color distortions due to different computer resolutions. There might be size errors due to different computer resolutions. 1 * Invisible ink pen. Spy Pen: a secret message is written with this invisible ink pen, only can you see it until shining it over where you wrote Invisible ink pen: the secrect message pens have the UV light installed in the cap so you don't need to buy a spare light, very convenient to use Birthday party goodies: Great goody bag treat and brings you an amazing variety of fun applications. Gifts, Halloween gifts, Christmas presents for friends Safe kid toy pen:Harmless and flavorless ink, you can write everywhere:T-shirts, paper, skin and any surface The inks is durable but washable, very safety to use, very interesting and bring fun for kids