Two of my yukiwatch 6538 cases have had problems with the threads the brevet crowns can not screw up tight and just pop out leaving the watch unprotected you can push the crown up to the case without it threading .
I have emailed yuki but they do not supply tubes only crown/tube sets do we have any other options ? i like the curved finish of the yuki brevet the athayia brevet crown is flat , but a very good buy.
I will order a helenarou crown tube to try but i think that the crown is 8.2mm size helenarou crowns have very good strong threads as fitted to my homage blackbay .