Energy Tube, teaching resource for an array of scientific concepts: open and closed circuits, conductors vs. Insulators, light waves, sound waves,currents, and energy, When a conductor touches both of the electrodes on tube, tube emits a sound and flashing red/green/blue LED lights
Spectrum Tubes Deuterium, glass tubes approximately 10-1/4in (260mm) long, central capillary portion approximately 3-1/2in to 4in (90-100mm) long with electrodes sealed at both ends and connected to lead wires protected by metal caps.