Nikon Mercury Fluorescent Lamp alignment objective.  This tool facilitates a quick and accurate alignment of the mercury fluorescent lamp.  Simply screw this tool into the microscope nosepiece turret in a blank opening or in place of an objective lens.  This tool fits microscopes from various manufacturers with 160mm tube length, 37mm shoulder height, DIN standard threads and a limited number of microscopes with infinity tube length - it does not fit Nikon Eclipse series microscopes unless and adapter is purchased separately.