A stall door with wings on either side, as opposed to a stall door with just one long side wing, is structurally much stronger. Now you can dictate the length of your stall to fit your space. In addition, the clear and open doorway that a centered stall provides means you're eliminating the threshold as a potential stumbling point. And, because your horses are now centered in their stalls, the nippers won't be able reach next door to annoy their neighbors, and the chewers won't be able to chew on those tasty posts. After all, we didn't design a centered door just for its good looks.