Mini Secret Diary With Invisible Ink Secret Pen.This Special Pen Writes With Invisible Ink That Cannot Be Seen By The Naked Eye Under Regular Light, Only Revealing The Hidden Messages Under The Built-In Uv Light Lamp At The Top Of The Pen,Allowing Kids To Hide All Their Private Notes, Doodles And Secrets Safely Inside The Diary As The Tagline Promises: Hide All Your Secrets In This Diary.