Perfect for maintaining an active lifestyle even in an office workspace. Very portable and easy to store. the GoFit Stability Disk helps you reach expandable fitness goalsincrease the difficulty as your ability improves. The firmness of the Stability Disk can be adjusted. For a less difficult. or entry level workout. use less air in the Stability Disk. As you increase your balance and strength. fill the Stability Disk with more air and move toward a higher level of difficulty in your core training.