The Isco-Gottingen Westromat 135mm f/3.5 is a telephoto prime lens for 35mm SLR cameras with the M42 screw mount.
This is a rather rare single-coated lens, manufactured in the 1960's. It is very difficult to find any details about this lens. It is supposed to descend from the Schneider-Kreuznach Tele-Xenar 135/3.5 lens, manufactured by the parent company. The lens came with the Exakta bayonet under the name of Auto Tele-Westanar 135/3.5. It is compact but rather weighty: the lens body is constructed from brass with darkening, black enamel.