This vintage Elgeet 4" (100mm) f/4.5 Mini-Tel manual focus chrome lens is for use with Clarus mount cameras. Its rear thread is 40mm. There are a couple of scuffs and scratches on the exterior of the barrel and there are a few dust particles inside of it. There are also a couple of cleaning marks on its front element. Its focus and aperture adjustments are both smooth and its glass is free of any fungus, haze, or separation to its elements.