Gamma “Duplex” Surveying Angle Prism with Original Fitted Case – Hungary, c. 1950–1970 A vintage Gamma “Duplex” surveying angle prism, manufactured in Budapest, Hungary, during the mid-20th century and preserved in its original fitted carrying case. This compact precision optical instrument was designed for geodetic and land surveying, allowing surveyors to establish right angles and perpendicular offsets during field measurements. Its internal prism arrangement enables the simultaneous observation of two directions, providing a practical means of alignment without the need for larger surveying equipment. Gamma Művek was an important Hungarian manufacturer of precision instruments, optical equipment and scientific apparatus. The Duplex belongs to a generation of compact surveying instruments developed during the expansion of Central European optical engineering in the mid-20th century. Of particular historical interest is its similarity to the later MOM (Magyar Optikai Művek) Duplex K440 angle prism. Both instruments reflect the tradition of Hungarian precision optical manufacturing, although their exact production relationship has not been conclusively established. The instrument features a black housing with a cylindrical handle, viewing openings and internal optical prisms. It is accompanied by its original compact fitted case, finished in black with a dark burgundy velvet-like lining, brass-coloured hinges and a decorative fastening clasp. The fitted case adds considerably to the presentation and completeness of this historical surveying instrument. - Dimensions of the closed case: 7.5 × 5.5 × 2.5 cm - Total weight including case: 125 g - Condition: Good vintage condition, showing age-related surface wear and handling marks on the instrument, together with some wear to the original case and its interior lining. The optical prism elements are present, but optical accuracy and full functionality have not been independently tested. An appealing example of mid-20th-century Hungarian precision engineering. Carefully packed for secure international shipping.