The Body-Wheels Full Body Workout System is designed to work multiple muscle groups simultaneously or can be catered to isolate a specific area for more strength and definition. The Single Arm Ab Tightener isolates your abdominal muscles upper and lower depending on how far one stretches for enhanced abdominal contractions. The Single Arm Ab Tightener isolates your seratus for enhanced definition, to give a more pleasing and shapely mid-section. Great for beginners as well as the most seasoned athletes a must to truly isolate those hard-to-target specific abdominal muscles. A slim tight mid-section is just a few short workouts away.