Pictured is a Nikon Plan 20X infinity corrected microscope objective that has a factory installed Hoffman Modulation Contrast retardation plate. The condition is new, still in original plastic bubble (not pictured). It is intended to be used on the current Nikon microscopes such as the E200, E400, 50I, and current series of Nikon compound scopes equipped with either a Hoffman Modulation Contrast condenser or a Modulation Contrast condenser. It is also very effective with infinity corrected Nikon inverted microscopes! The working distance is 1.3 mm, na is 0.40 and thread diameter is 25mm. When the microscope is equipped with this objective, a modulation contrast condenser and a polarizer, images approaching DIC quality can be obtained. The condition is new, never mounted on a microscope.  These objectives don't come up for sale on eBay very often. Thanks for looking.