Stereoscope slide viewer, collapsible type

Nickel plated brass stereo viewer designed for use with stereograph cards. One end of the viewer contains two variable separation lenses, and at the opposite end is a folding frame to hold the stereograph cards. The centre section contains a sprung 'U' shaped handle and a rack and pinion system which is used to lengthen or shorten the distance between the lenses and the card frame. When not in use the viewer collapses flat for storage.

Unknown.