This "Turmon 8x" folding Monocular was made for carrying in your pocket Folded flat it is only 25mm X 45mm X 70mm. The image is inverted until the two halves are rotated 90 degrees. By doing that the image turns 180 degrees. There is a focusing adjustment on the eye piece.
The Turmon was produced from 1921 until 1990.
This nice Turmon is brand new and from 1952. It has coated optics.
After the fall of the Berlin wall in 1989, Docter (the old Zeiss Jena) still produces this nice Monocular. Nowadays the housing is made of Glass filled Polycarbonat. The lenses are fully multi-coated and the prisms are Bak4. ( link to the Docter Turmon )