Olympus UPLSAPO10X UPlanSApo 10x/0.40 8/0.17/FN 26.5 Microscope Objective Lens. Bought new and the objective is still almost like new. I take very good care of my optics. Photographs taken with this objective can be found in my portfolio.
Also see my other listings for the rest of the SAPO-series (4X-100X).