Hi Jennifer. I believe Cathe is using the Super Step Bench System. It is also made by The Step Company. It has two large "risers," and the bench goes from approximately 5 inches (top only) to 10 inches (top plus one "riser") to 15 inches (top plus both risers). I bought one when I first decided to try working out at home, and before I even started buying Cathe DVDs (and before I really knew what I'd need). It is good as a workout bench, since you can bump it right up to 15 inches and it inclines/declines nicely. However, I quickly learned that you really can use the original step as a bench if you just stick a few more risers on it, so I definitly would have been fine without it. Oh well.
Hope that answers your question. Have a great day.