Lots of Tweeters looked like that not just the Shacks.Pretty basicCould be a DIY ? Looking at where the edge of the baffles meet gives me a DIY vibe. Pull the drivers and see, I bought a Radio shack tweeter that looked identical to those years ago.
No inset. Just a simple rectangular plate mounted with 2 screws.Are they inset like these, but with spring terminals? I replaced this one with binding posts.. some had a silver backing instead of the gold on this one.