Zeiss 25mm Orthoscopic Ocular(3-Element Aspheric Design), with 18mm field stop giving a 42° fov, generous 20 mm eye relief and diopter focusing.
This is a superb "Super Flat-Field" microscope ocular manufactured by Carl Zeiss Oberkochen Microscope Industrie and, unlike most microscope oculars, is perfect for use in astronomical telescopes (APM gives it high marks as do I, based on actual shoot outs vs. other premium oculars in its f/l). Zeiss has applied its excellent ZHFT-Multicoatings to the best grade Schott/Germany glass to achieve the highest possible light transmission. The light throughput, contrast, color correction and sharpness of this ocular is simply unsurpassed, as you would expect from Zeiss. The barrel is a custom machined black anodized aluminum adapter providing a snug fit to standard 1.25" ocular tubes, and it is threaded to accept standard 1.25" filters.
I've got two more that are identical except for their field stop being 3mm wider, and being consequently more expensive, that I bought as a matched pair for binoviewing, so I just don't need this one. Great as a single or buy a second for terrific binoviewing.
In very good condition with pristine optics and coatings.
APM sells these new for about $167, excluding $25 insured shipping to the U.S.
$125 shipped Priority Mail, insured, to anywhere in Conus.