Bud Lyon breaks down the imaginary box, the standard he uses to measure whether a horse is truly responsive. Picture a tight window from the base of the neck to the top of the saddle horn and about two inches either side of the mane. If Lyon can steer, rate speed, and get collection with his hand inside that box, the horse is as responsive as he wants, and it translates straight to the show pen. If his hand has to travel outside it, the horse isn't listening well enough yet.