The Fitness Circle Pro is a must-have for all Pilates instructors. Used on the Mat, the Reformer, or other equipment, this portable piece helps maintain proper alignment. The Fitness Circle Pro is made of spring steel and built to withstand continuous, high-intensity studio use.The 12 inch version provides a firm resistance and it’s recommended for people 5 ft 4 in (163 cm) or under.Add resistance for upper and lower-body exercises—the Fitness Circle Pro improves muscle tone and is great for problem areas that are hard to firm up: inner and outer thighs, upper arms and chest.