The item is a Secret Message Invisible Ink Pen with UV Light. It can be used to communicate secret messages to your friends. Simply write a message with the invisible ink pen, then light up your message with the mini UV light; to see what was written down. Features - Color: Black. - Material: ABS. - Size: About 13.5 * 1 * 1 cm/ 5.3 * 0.39 * 0.39 inch(L*W*H). - and high quality. - The ink is invisible after you write with it, unless you light on the blacklight to see the secret message perfectly. - Flavorless and ink, to kids; It can be wrote on T-Shirts, paper, skin! Permanent but washable! (Please do not use on some special surface, like: glass or smooth plastic film, etc; it will influence the effect, and easily to be erased.) - Halloween Party Goodies: Perfect for the RSVP's to wedding invitations; Goody bags for kids spy party; Make a fun party favor; Great goddie bag treat and brings you an amazing variety of fun applications. Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Sold by-Dadangjia