A folding metal stereoscope for viewing pictures in 3-d. This a norweigian stereoskop made by the Norsk Stereoscop Forlag in the 1920s. The pictures are also from this company. Using this stereoscope is easy and straight forward: Apicture was placed inside the two metal crevices. While looking into the two lenses at once, the picture can be focused by bending the sides of the apparatus towards or away from the eyes. Size when folded is 12.5 cm X 9 cm.