Integrating a simple box in to your workout opens up a whole new Realm of movements. I'm REALLY excited to bring it to CDM. I use a Reformer Box (Sitting Box) which I had at home and it's 11.5" high. It's a bit tall and clunky. Any Step will work. For height, I wouldn't recommend going over the height of this Sitting Box. Check out Amazon or your local Sports store and get ready!