From MURPHY'S MAGIC, created by Lloyd Barnes. This is the black light version of double cross, where an X mark written on the hand with a black pen moves. I purchased it in a lucky bag and opened it, but I have never used it. The following is a quote from the product description: You start the performance by giving the audience a UV light and a special UV pen. Using the special pen, have the audience write an "X" mark on their own arm or hand, wherever they like. When you shine the UV light, the "X" can be clearly seen. However, if you continue to shine the light, it will slowly disappear. Next, have the audience shine the light on the performer's arm, and the performer will reveal an "X" slowly appearing from nowhere. This is not a CG video! It happens in reality. It is probably not an exaggeration to say that this is the closest phenomenon to real magic! This is just one example. Please check the trailer! "The audience will have a very powerful experience. If real magic existed, it would look like this!" - Tobias Dostal ・ You can perform it in combination with phenomena you are already performing, or you can add more surprise to mentalism. ・ You can perform a very clean "Invisible Deck" phenomenon, or you can perform lottery ticket prediction phenomena and book test phenomena. ・ It has various possibilities! "It's a visual, surprising, and easy-to-perform special phenomenon!" - Adam Wilber You can even have the audience trigger the magic! It's that easy to perform! You can concentrate on the performance and direction without worrying about difficult handling. The online video explains in detail the basic handling, as well as various routines, ideas, and points.