Fun and Creative: Invisible pen are a fun and engaging activity for people of all ages, allowing for a unique and imaginative way to express messages with friends and family, strengthening their bonds (Please note: All the inks are invisible and the UV lights are purple) Safe and Non-Toxic: The package of 16 magic pens is a great addition to kids' parties or classroom activities. The invisible ink is safe for kids to use, but children under 3 years should use it under the supervision of parents Secret Message: Who doesn't love leaving secret messages to surprise their friends? Anything written on paper, skin, walls, and shirts stays hidden unless you shine it with the UV light Perfect for Party Games: The magic ink pen set is perfect for kids' party supplies, such as spy birthday parties, escape party favors, magic party favors, Halloween parties, piñata stuffers, and many other occasions Perfect for Parties & Gifts: A hit for kids’ birthdays, classroom rewards, Christmas stockings, Easter baskets & more – fun, unique