Bakelite Stereo Viewers (various)

lot of six stereo viewers by various makers made of Bakelite or early plastic, (1) dark brown viewer with metal front produced by NovelView (New York) for transparencies on uncut 35mm film, the images are transported with a simple knob on top of the viewer, the stereoscope is in very good condition and comes with ten filmstrips, nine of them in the original box, (2,3) two nearly identical stereoscopes with low voltage electric illumination, the black one labelled 'Keys Stereo, the one with faux-wood finish labelled 'Haneel Tri-Vision', both showing some wear, otherwise in good condition, (4,5) two identical 'Colorscope' viewers, the red one in perfect condition, the one with faux-wood finish shows some wear, (6) simple unlabeled viewer for transparencies. (6)