Electric circuit labs will be buzzing with this easy-to-wire device. Students will enjoy the buzzing sound signifying a successful completion of a wiring circuit. Pressed-steel outer shell provides for long-term, heavy-duty student use. Requires 6 to 10 volts AC or 3 to 6 volts DC to operate. Overall size 2-1/2" wide x 21-5/16" high x 1-1/16" deep.