Foosball.
If you look at the ring, there is a slot then an hole alternating around the ring. Slip in the end, drop in the handle side. I would suspect handle clearance and also -when cutting the metal to form the ring, too many cuts in the edge may make it harder to shape and hold its form.
They had a heck of a time getting the center section of the WSM to hold it's shape and form due to the large rectangular cut out. It wants to kink there.