I cant find enough information on these and the book "the kardon story" is out of print. I will be sending off to cleaned soon. I have leica IIIb the finish of the chrome is not as nice as the leica but its not bad it's covered in leather shrinking a bit around the lens mount. Operation seams to be relevantly smooth. I ran film through it focus looks to be spot on. The black knob is a curiosity it is not painted over chrome there is some brassing so I think it's the original finish .