They're great little cameras, if not quite as refined as later variations of the CS-1. All FX-3's have the small shutter release and lack the shutter lock, the FM10 introduced a larger release & a shutter lock which improved handling.
The base camera is the Cosina CS-1, which has two variations, a manual, mechanical camera and an aperture priority electronic shutter camera.
This camera has been sold under a number of different names. The Mechanical version was also sold as the FX-3, FX-7 (same camera in silver), Ricoh KR-5 family, Nikon FM10, Voigtlander V3000, Vivitar V4000, Voigtlander Bessaflex TM (with metal top & bottom cover), Olympus OM2000 (with selectable spot metering) and the Canon T60 (with horizontal travel shutter). They also form the basis for the mechanical Voigtlander Bessa rangefinders and the Zeiss Ikon SW.
The aperture priority version was also sold as the Nikon FE10 and forms the basis of the Bessa R2A, R3A, R4A and the Zeiss Ikon. There may have been other variations as well.