Invisible ink pen: Write your secret message with these magical UV pens! The ink is invisible unless you shine the UV light on the cap to reveal the hidden message clearly. Safe and non-toxic: Made of ABS plastic with a button battery included, the invisible pen with UV light is non-toxic, harmless, and odorless. Suitable for children aged 3 years and up. 7 colors: The UV invisible ink pen comes in 7 exterior colors, but the ink itself is a single color. Suitable for any occasion: These magic pens can be used on T-shirts, paper, skin, and any smooth surface. Encourage creativity through writing, sketching, and drawing secret messages. Creative toys for kids: Children can use the spy pen to keep secrets and play detective or spy games. Surprise family with secret cards on Mother's Day, Father's Day, Halloween, Thanksgiving, or Christmas. Ideal for schools and teachers to use in classroom activities.