Horses are designed to eat off the ground, but to avoid the chances of them eating dirt or anything besides feed (which can cause colic) a feeder should be attached to a stall wall at about 3 feet high. Be sure to get a feeder large enough to allow them to spread their hay around a little, otherwide I find mine just throw it all out on the ground and then sift through it. Wach out for feeders with a narrow opening, like the old metal ones with a wide brim, they can lose a lot of skin around they eyes if they are startled while eating and lift their heads too quickly. Also, if you feed any grains or supplements, beware of buckets! I've had a couple of horses require stitches after catching their nostrils on the turned up ends of the handle. There's a new product out to solve this propblem - its a small piece of neoprene that velcros around the turned up part of the handle. It works great.