WQQZJJ Multifunction Luminous Light Pen Toy Pen Fine Tip Invisible Ink LED Light Student: Specifications: Color: Red, yellow, green, blue, purple, black, Weight: about 10g Material: plastic Size: about 13.5x1x1cm/5.31x0.39x0.39 inches Package includes: 1X invisible ink pen Note: Please Allow a little Difference Due To Manual Measurement.Besides Different Computers Display Colors Differently, The Color Of The Actual Item May Vary Slightly From The Below Images Thanks For Your Understanding(1 inch = 2.54 cm),Please Kindly Check It Before You Order Our Product,Thanks. Built-in light, children will write a lot of messages to each other, invisible to the naked eye, light will appear on the text Note: You can write on most surfaces, but whether you can stay on the surface depends on what you write. If you write on paper, it can be kept forever; if you write on metal or plastic It may last long because it can be easily erased due to the properties of metal and plastic. The perfect gift: With pens, you can let every student in the classroom of every guest in the office have their own pens, so you can make cool party gifts or birthday gifts.