This Helium Spectrum tube gives premium performance at an economical price. Lethan Corporation designed these spectrum tubes to deliver excellent spectral clarity and minimize spurious emissions compared with other manufacturers spectrum tubes in the same price range. These tubes can be utilized in most standard spectrum tube power supplies and thanks to the loop terminals can be hard wired to any high voltage supply (induction coils, Wimshurst machines, Van De Graaff generators, etc.) up to 5 KV (3-5KV Recommended). These spectrum tubes provide a large 4" / 10cm capillary viewing area in the center.