Nikon CF Achromat 40X Long Working Distance (LWD) Microscope Objective.  It will fit the Nikon Diaphot TMD and TMS of 160mm tube length  inverted microscopes. It will work very nicely in both inverted and upright microscopes from other manufacturers such as Olympus, Zeiss and Leitz.  This is an CF Achromat Brightfield Lens with coverglass correction collar capable of correcting for thickness of 0 mm to 2.0 mm. and the numerical aperture is (n.a.) 0.55. These lenses are used but in excellent cosmetic, mechanical and optical condition with all glass being free from fungus, dust, scratches or element separation. The correction collar moves smoothly and has been recently serviced.