F. Koristka Milano Monocular Microscope (No. 30671) With Slides, Mahogany Case & Key. Circa. 1920.A substantial brass monocular microscope, model no. 30671, by F. Koristka Milano. The microscope is housed in a fitted mahogany case typically made by Zeiss. Zeiss supplied Koristka so it is possible that the case may be original to the scope. The box has a working lock and key. The microscope has two objectives. All lenses are intact and the microscope is in good working order. The microscope comes with several early 20th century slides, namely: Wing