The 2-In-1 Invisible Writer Pen from Toysmith lets you write both invisible and normal ink messages. Each pen is a translucent purple with a black light in the cap. Press the yellow button to activate the light to read messages written in invisible ink. Each pen also includes either regular black or blue ink for everyday, visible writing use. A peggable plastic package contains 1 pen with instructions for use. Get 21 individually packaged pens with a purple display box.