I use 55 gallon plastic barrels. We cut out a large opening on the side of the barrel. Then on the opposite side of the opening we drilled small holes for water and dirt to fall through. Our barrels are then placed on a cinder block (1 at either end of barrel) to raise them up so the dirt and water can drain out and then they are hooked to the fence. The openings are large enough for the horse to put their heads in with no problems. We also fluff the flakes of hay so they fill the whole barrel and they tend not to through the hay out of the barrel. Our old horse is unable to eat hay so he is on a grass pellet and senior. We add a little water to his to soften the pellets so the extra water drains out the bottom keeping the barrel clean. Our feeders are mounted pretty much on the ground since this is the natural way for a horse to eat and keeps dirt, mold, etc, from being inhaled. Keeping their heads down keeps the airways clear.