This LED illuminator replaces the original Olympus BX50 bottom illuminator. It gives a whiter, brighter light than the original, while using 1/10 the power. Never change bulbs again. Intensity control is continuous from 0-100%. As of October 2019 the Nanodyne replacement for the BX50 illuminator includes its own collector lens, rather than the lens from the old illuminator. This makes the installation even easier than before. It attaches to the microscope just like the original Olympus BX50 bottom illuminator. Just loosen the screw in the microscope to remove the old illuminator and replace it with the new Nanodyne unit. Please check the blue installation link below for complete details about connecting the intensity adjustment.