Olympus Microscope Objective Lens E A40 40x 0.65 160/0.17 Japan

  
Numerical Aperture (NA): 0.65. Tube Length/Cover Glass Thickness: Indicated by "160/0.17, " meaning it's designed for a 160mm mechanical tube length and a 0.17mm cover glass thickness. Type: It is a spring-loaded objective, meaning the front element retracts slightly upon contact with the slide to prevent damage.