I don't think they make those anymore. They aren't as versatile as the 'regular' step. I think you could use it as an aerobic step only without the risers. With the risers, it'll be too high. I'm not sure that it's smaller either.
The regular step can be used as an incline with the slanted risers. You can vary the step height to fit your need in 2" increments. You can make a high step using the high topper.