Every when does so black hardware become available?

Don't know about rectangle/square but they had a woc with turnlock closure in saks in new york.....I got one! I think it fits very similar to square mini flap if you put a woc saver.....
 
No idea where you are but i think there is one available on designer wish bags. It’s an European on line store. Of course have it authenticated first if you want to go ahead with that one. Goodluck with your search.