This is a brand new microscope Kohler illumination device with built-in iris field diaphragm. The primary advantage of Kohler illumination is the extremely even illumination of the sample. The Kohler illumination provides high sample contrast. It is easy to upgrade your transmitted illumination system of microscope to a kohler style in 1 minute. This type of Kohler illumination works with our compound micrscopes with S-LED light.