Not sure about the bottomless feed bunks, but this year, for the first time, we bought and used the concrete feed bunks. LOVE THEM! They are heavy, and indestructible! We bought them for the bulls we develop, and they have yet to move an inch. They were cheap ($125), cheaper than the plastic bunks sold, and I can see these things outliving us! We will definitely add a few every year for each pasture. I think they would be great to put mineral in, if they are out of the elements.