BOSU ball is a fitness training device, consisting of an inflated rubber hemisphere attached to a rigid platform. The device is often used for balance training. When the dome side faces up, the BOSU ball provides an unstable surface while the device remains stable. This combination of stable/unstable allows a wide range of users, from the young, elderly, or injured to the elite level athlete. With the dome side up, the device can be used for athletic drills and aerobic activities. The device can be flipped over so that the platform faces up. In this position, the device is highly unstable and can be used for other forms of exercise.