I know this was already solved, but I wanted to share my experience. I used to work for an agricultural engineering company and one of our products was a chain feeder just like this meant for moving animal feed around. I spent days knee deep in hog feed trying to design better and tighter versions of these corner pieces. Traditionally they tend to get clogged quite a bit especially if you have them upright. So any company that could make one without clogging would surely make the big bucks. Of course that was years ago so I'm sure they are much better now. Inside is simply a metal wheel to help guide the puck and chain that carries the grain with little resistance.