An easy way to light up the kids' eyes! Teach them to wire a simple circuit with our basic components. The knife switches are mounted on a plastic bases. The miniature plastic socket holds a standard flashlight bulb with a 14 mm dia screw base. We pack 6 volt and 3 volt round bulbs, or 1.5 volt bell-shaped bulbs, (5) to a package.(Bulbs are rated slightly higher to prevent them from burning out.) Hook up the black plastic and metal 2" x 4-1/4" telegraph key with brass contacts and (2) terminal posts with nuts. Our blue-plastic holder for (1) "D" battery has a small tab at each end to hook a lead to, and a 1/8" square mounting hole at each corner. You add the mounting surface and the know-how. Actual bulb voltage listed in parenthesis.