Reichert 100X plan achromat oil immersion microscope objective.  The Reichert part number is #1736 and can be used on the Reichert, Leica or Cambridge Microstar IV or model 410.  It is also compatible with the current Olympus BX series of infinity microscopes.  The objective is infinity corrected and requires use of a cover slip thickness of 0.17mm.  The NA is 1.25 and the glass is free from fungus, dust, scratches and oil incursion into interior elements.