Spezial-Anastigmat 5cm lens. Contax mount for Contax 1 or the external Contax mnount. Made in Germany. Has no aperture or focusing feature. These can be mounted to the camera as a lens cap lens focused to infinity, as in the photo (CAMERA IS NOT FOR SALE WITH THE LENS) and also used on the Zeiss enlarger or bellows for close focusing. Lens has been cleaned behind the front element but not totally disassembled. It is most of 100-yeras-old