To study Spectral Lines of Pure Elements / Gases. Gas under pressure in the tubes is used to produce a light for spectral analysis. Brightness of light depends on the nature of gas. Optimum intensity, line resolution and longer life. Metal ends with long life electrodes. About 26 cm long, with 90 -100 mm of central capillary. For intermittent use only, not to be used as a lamp source. These are designed to operate 30 seconds ON~30 seconds OFF. Need Spectrum Tube Power Supply or an Induction Coil, sold separately.