Nikon CF-phase contrast 100X oil immersion microscope objective Ph4. This objective was rarely used as a dealer demonstrator and is in perfect condition cosmetically, optically and mechanically. It has been tested and the images are superb.  This is a spring loaded, 160mm TL (tube length), DL (dark low), phase ring size Ph4 objective. It is meant to be used on 160 mm TL microscopes such as the labophot and optiphot 1 and 2. It was also used on the alphaphot, microphot and TMD inverted. A cover slip size of 0.17mm has to be used and it has an NA of 1.25. The Nikon product number is 79583.  Objectives of this age and quality are extremely rare to find! Thank You For Looking.