A 146 with a transparent body is either a Skeleton Edition (with skeletonised metal surface and translucent background) or a demonstrator (demo fountain pen). Demonstrators were originally produced for training and demonstration purposes in boutiques and are only available in very limited numbers, accordingly sought-after and expensive. They differ from the regular model only by the transparent body; all other components (nib, mechanism, cap) are original Montblanc. An overview of the Skeleton Editions can be found at fountainpen.de/skeleton.htm.