This traditional task chair is the right choice for durability and mobility needs. The chair has a one-piece polypropylene shell and tapered opening in back to eliminate pressure points and provide lower back support. Choose your seat size: A or A+. The A+ offers a wider more accommodating seat. The sturdy 5-star base has a 24" diameter, swivels 360 degrees, and features durable 2" dual casters. With an adjustable pneumatic height of 24"-34", and simple turn handle to adjust the 18"-foot ring this chair is comfortable at any height.