Any X-ray source which combines mono-energetic radiation with the benefits of a switchable electrical device could be an interesting alternative. We will outline the design of such a new, nearly mono-energetic X-ray source. The major properties like spectral purity, stability and radiance will be presented in comparison with a radio-nuclide and a conventional, monochromatized tube. An outlook will be given of potential application areas, especially in NDT, for the characterization of materials under investigation.