I bought Hiwin carriages&rails directly from Hiwin Germany in the past. So these are proofed genuine. The carriages are also not moving by their own if you hold the rail at an angle. The reason is that if it would then the carriage would be sitting too loose on the rail and vibrations can have a negative impact on the component screwed to the carriage. Instead the carriage has to run smooth on the rail without any hickups (which one of mine does not) but there should be some slight resistance when moving it.