Train your students to be Private Eyes! Private Eye Loupes, simple 5x magnifying lenses, are perfect for large and small hands alike! Used throughout The Private Eye book. With the Spy Pen, write with invisible ink and use the special, attached ultraviolet light at the other end to read the message. Both our large and small UV Flashlights come with a black filter to block much of the white (visible) light, making them ideal to use in any light. Great for finding clues in your investigations!