How does this heater box retainer rod (J-hook) work?

As stated, the hook end of the rod goes up. It goes up through the round cowl opening and hooks on the edge of the hole. The bottom of the rod should be bent at a right angle with a flat bottom. The flat bottom of the rod goes between the ribs in the bottom of the box to prevent it from turning when you tighten the attaching bolt that goes up from the bottom on the outside of the box. The flat bottom of the rod should have a hole that is threaded to accept the bolt.