Children, listen to Grampa...back in ancient times there were French-threaded freewheels and these were usually branded Atom or such and will not thread onto Italian or British theaded hubs. These Frenchy FWs and hubs are pretty rare, but you might still chance upon them. The Italian and British threaded hubs/FWs are more-or-less compatible, the only diff being the thread ANGLE (55 versus 60 degrees, I think) so these are "universal" being the standard that the Japanese adopted. All your commonly available Shimano, Suntour, Sachs, Chinese, Indonesian FWs will be this BSC/ISO/JIS standard thread. As Johnny Law once said:"If the FW don't fit, you must quit" so don't force a FR thread onto a ISO hub or vice-versa