Helps strengthen and stabilize your muscles that control balance and movement. 39cm wide and is easily inflated without a pump, the air can be added or removed to make the balance more difficult or easier, an excellent progression exercise tool. Can also be used as a seat in place of a gym ball which can be as demanding but easier. We offer the greatest quality products at the lowest prices. Please note that you are purchasing one balance pad - our photograph shows 2 pads to demonstrate the 2 different surfaces. If you are looking for superb value on Amazon then look no further than Physique Management!!