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.