Leave secret messages in a subtle and sneaky way using these Confidential Secret Decoder Spy Pens! A clever addition to school supplies and everyday essentials — as well as espionage supplies — these pens can write in normal ink to keep your cover intact and keep suspicion at bay. But they also include invisible ink for your most confidential secrets and an ultraviolet light so your "colleagues" can reveal and decode those messages. Play spy or just leave fun messages for your students or kids to find! Black ink. Plastic. 7 1/2"