Is there a threaded 3/8" hole at the bottom of the "hot shoe" base or is it just flat?
DAVID L M
The two knurled thumb-wheels each have a threaded 3/8-16 hole. There are no other threaded holes. The "shoe" portion has simply a flat surface with no hole in the center.
BTW, this thing is VERY strong and well-made. Whatever you attach with this thing is as secure as the hot-shoe or the cold-shoe receptacle itself.