1. Ab Rocket ($100): Most Ab Rocket exercises were slightly less effective than traditional abdominal exercises in our tests, and the head position bothered some. Diet plan was sound but lacked specifics abut food amounts and diet duration. Good for most beginners, but we found sit-ups slightly more effective.

2. Rock-N-Go Exerciser ($230): Panelists agree that the machine was easy to use, but they didn't feel it provided a workout. Some felt ridiculous or creepy on this machine. Our tests showed it was less effective at engaging abdominal muscles than conventional exercises performed with no equipment on an exercise mat.

3. Red Exerciser DX ($175): As we reported in February 2008, the "core twist strides" in the infomercial and some advanced exercises in the video engaged obliques at least as much as comparable floor moves but might not work abs as well. Good for obliques, but those 4 inches aren't going anywhere without serious dieting. Diet plan provides sound advice, but no maintenance plan.

I don't own any of them, but thought this info might be of some help. Good luck!