This is a pen that allows you to write with ink that reacts to ultraviolet (UV) light. It's a set of two pens offered at a low price. How about one each for siblings? The writing appears and becomes visible when exposed to UV light. The UV light is built into the pen cap. This item is new. Please check the photos for the pen's shape and how the writing appears. *We have multiple items in stock, so if you need three or more, please let us know in the comments.