I've used vinegar to take the jet black finish off the SM7 so it will rust, and after doing so there's a rectangular section about 1" long and 0.5" wide in the dead center of the sole that looks like steel was added and buffed before the finish was applied. Anyone have any idea what this really is?
It's metal for sure, and completely smooth. Not the remnants of a sticker or anything like that, best I can fathom.