Note: There are some elementary schools that are used overseas as as chairs and are effective for childrens education and development. Even adults can use it to improve their posture and alleviate lower back pain. As seen on TVs, this item is a popular item. Considering the use of sitting, there are 6 to 8 feet for stability but you can perform the same exercise as a gimnik ball. Perfect as a birthday gift for a child. Note: Air pump is sold separately. A-LP-9904 Gimnik Ball [Air Pump DX].