Balance DiscWork your abs from the chair of your choice with a posture improving inflatable Balance Disc. The Balance Disc engages your core muscles while sitting and can also be used for strengthening exercises in your chair or on the floor. By controlling the firmness of the cushion, you can adapt it to your fitness needs and sitting comfort. Does not include a pump. Strengthen your core and improve posture as you sit comfortably Use with a variety of strength