F-21, KMZ,  USSR,   1950s-1980s 
 The camera was Originaly made for the KGB or STASI as a concealed spy camera. No label or any markings of the manufacter on the camera.

 F-21, Button camera
 A concealed version of the F-21. As seen at the photo bellow, the shutter at front is designed like a button looking like an innocent button in a coat when the camera body is concealed behind the coat and the shutter release is at the pocket of coat.
Some versions exist, some to be concealed in bags etc. Those sell good but Supply exceeds demand. Who knows, maybe those cameras are still in production even nowedays.