The hard-to-copy Chinese mail keys.

I tried to copy a mail key this week. The self-service machine wouldn’t do it. The key desk at Home Depot couldn’t do it. I finally took it to a locksmith, who, before even seeing my key, warned that he couldn’t copy Chinese mail keys. I wasn’t quite sure what was so special about these. Judging by this reddit thread, I’m not the only one who’s faced this challenge! | learn more