Mark your personal property discreetly with our Invisible Ink I.D. Pen & UV Light. This pen allows police to detect, identify and return stolen property fast in the event of a burglary. You simply mark your valuables with your name and phone number. This pen is PERMANENT on most SURFACES including glass, paper, wood, plastic and cloth with long lasting, invisible ink. Only under an ultraviolet light do the marks become clearly visible to police, detectives, and pawn shop owners. One pen will mark over 1,200 valuables. Can also be used to write personal messages that will only be readable under a UV light, also making it a great gift for that “spy kid” in your life! The Ultra violet key chain light comes with the battery already supplied. Have fun. It works Great!