Part 1  Randy demonstrates how he varies the head set according to the age of the horse before he works in the Post Pen. He also explains how the Post Pen is great for developing a horses patience, so they are comfortable waiting for your cues. ” Good exercise to get their brain on your side and teaches them to use their body and be athletic”, Randy says. He also explains how it helps a horse get comfortable to do a slow lope and sharpen up a stop.