The Alvin Pneumatic-Lift Stool (Black) is perfect for any home or office work area that needs drafting height. Ideal for extended sitting periods, it has a swivel feature, pneumatic height control and an adjustable height between 18" and 26". The 13" diameter seat is made of super-soft molded foam. It also features a stable, 22" diameter, 5-star base on hooded casters. It is puncture resistant, easy to clean and maintenance-free.