Vintage German Isco-Gottingen Vario-Kiptagon 16.5-30mm 1:1.3 lens for 8mm cine film projectors.  The main barrel section is approx. 29mm in diameter – I’m not sure which model of projector it would fit.  The optics appear scratch free, but there is some internal fogging and some condensation spotting under the front lens, as per the photos.  Otherwise, in good, used cosmetic condition.  It has no box / end caps.