I was making the comparison to Cole Jaws, which you can’t use either on a natural edge bowl.
I don’t actually turn many bowls and have no interest in natural edge anyway.
A Doughnut Chuck can also be used to finish off hollow forms and vases.
Edit: Thinking about this further I think you’re wrong Pete, you probably could use a Doughnut Chuck to turn the foot on a natural edge bowl if you support the centre of the piece with some sort of padding.