It is true that necessity is the mother of invention. We originally had these
made for the Wingabago travel carrier. Why use a non-stainless ring that will
ultimately rust with food and water bowls? We took control of quality
control and made this stainless cup and wire ring combo. It's rugged, and will
take the abuse of the travel carrier. The cup is 3 3/4", and the idea caught on.
People wanted the stainless ring/cup combination for their cages as well, so
we are selling them separately. These work in indoor cages, outdoor flights,
and of course the Wingabago carrier.