This is an Agfa Karat 36. It has an Agfa Solinar lens (a Tessar type lens) and it looks a lot to me like it might have been developed to compete against the Kodak Retina II or IIa. I wouldn't swear to that though. Anyway, it is a rangefinder camera, it uses 35mm film, it's been cleaned, lubricated and adjusted and it all works as it should.
Yes, a nice camera indeed. I apologize but when I first saw the title I though "Karat" was Karkat. ^ _ ^
Well it isn't a Karkat, but it is a very good camera of it's type (fixed lens rangefinder). It's small, has a very good lens, and focusing is very precise. Photos from it tend to be very sharp.