This unique addition to a hand-held Oudin Coil ('Tesla Coil') replaces the standard issue 7/16 in. brass probe. Screw in an ordinary clear light bulb and it turns your Oudin Coil into a great high voltage demonstration! Easily lights fluorescent tubes, neon lamps and creates mysterious sparks of electricity between your fingers and the bulb. Note: requires a hand-held Oudin Coil (Item HS-10) and light bulb, not included. Visualizer and Bulb each sold separately.