Beginning Spring 2014, each Pak-o-Bird includes two King's Cages 5 oz. stainless steel cups with the double bolt. It is a patented product with the Quicklock design that prevents the bird from removing the cup from the holder/ring. The double bolt design also avoids the cup from tipping or turning.
The airline carrier includes two cups with the single clamp. The cups are close to the floor and the single clamp/screw allows more flexibility in placement.
I have a very small Bourkes Parakeet, still quite young. Most food dishes I have found for a small bird are either way too big or uncomfortable to use. These are just the right size, and so glad I found them!! Now, the trick is, to convince the bird that she should actually eat her food and drink her water from them.
This really could have been shipped much cheaper than it was.