http://www.cameraeccentric.com/html/...llensak_5.html The 10" (254 mm) is the one you want. Also sold as Tele-Raptar.

Similar lenses include Rodenstock Rotelar and Schneider Tele-Arton. Schneider info here: https://www.schneideroptics.com/info...es/tele-arton/