Zeiss 40X Phase Contrast Water Immersion Objective Ph2. The cosmetic and optical condition are excellent with no internal element separations of delaminations. This objective is intended to be used on the 160mm Tube Length microscope from Zeiss such as the Standard, Universal,  Photomic and Ultraphot. It may be possible to use it on other 160mm microscopes from Olympus, Nikon, and Leitz but will not guarantee the phase rings will match-up. The NA of this objective is 0.75 with a working distance of 1.6mm. Thank You For Looking!