Gotcha GadgetsWhat do you get when you cross a hands on science kit with a whoopie cushion? Gotcha Gadgets, a set of customizable, constructible electronic gizmos along with an entire book of games, pranks, and jokes that make the most of them. Follow simple instructions to make a door alarm, motion sensor, light sensor, or push button sound machine, and then program it with one of four funny sounds. 9 volt battery required. Not included. Comes with: circuit board