Olympus Microscope 1.25 NA substage condenser. It will fit all of the BH/ BHS and BH2 microscopes as well as the BX40 /41/ 43/ and 45 series. We have several in stock, all of them are nice and optically good. Oil does not foul the substage diaphragm so they are mechanically good. Since they are used there will be a few minimal cosmetic marks on the black finish. Thank You For Looking!