It's the red and black dohicky you see the white and blue rope hanging from. As I mentioned in the rigging post, we were experimenting with a hand loop, which is what the white and blue rope is.
The reason for the experimentation was that Davan hasn't gotten a lot of good use out of the swivel. For a while she was using it with one of her rings, but she had a hard time getting it to the right height and it isn't easy on your hand to hold onto a plastic ring while spinning. The homemade hand loop did not work well, either. The rope really cuts into one's wrist when one tries to hang from it.
Yesterday, though, I got an idea using equipment she already owns.
Now she can spin to her heart's delight.