The famous prototype Hektor 12.5cm comes with a direct M39 mount and rangefinder coupling. It features sophisticated construction, sharing only a few parts with the production Visoflex-mount Hektor. Constructed from lightweight aluminium instead of brass, for better balance when mounted on a camera; its aperture ring, knurled similarly to the rigid Summicron 5cm, rotates in a different direction and is equipped with a broader focusing ring, among other features. The lens is in excellent condition, featuring very good optics. Few examples of this special lens are known to exist. This particular example is featured in Lager's 'Lenses' on page 95, alongside the slightly different model no. 0000151. It comes with a standard hood and both caps.