Milliard OfficeFit Fitness Ball Steel Chair A great alternative to expensive ergonomic office chairs that has premium fit-and-finish with no complicated knobs or levers to operate. Works just like a regular rolling office chair, but a fitness ball replaces your seat. As you sit and maintain balance, your body will naturally straighten your back to keep its center of gravity. Bounce happily to music, stretch when youre bored, or exercise quietly at your desk as you type. Now thats multitasking! Includes inflating pump, 17.5in. fitness ball, and steel rolling base with locking bar and seatback.