BEVCO's 9000 Series of seating provides advanced ergonomic features and total body support for all-day comfort. Featuring a large, comfortable waterfall seat and your choice of three large backrest sizes, these chairs offer around-the-clock reliability in a variety of workplace environments. Each chair features heavy-duty construction, easy-to-use ergonomic chair controls, pneumatic seat height adjustment, 360-degree swivel, sturdy five-legged highly polished cast aluminum base, and mushroom glides. Optional casters include hard floor, carpet, interval brake (lock when not in chair) or reverse brake (lock when sitting in chair) designs. The 9000 Series seat features resilient high-density foam for long lasting comfort. Backrest styles are uniquely shaped for full back support and come standard with a heavy-duty polypropylene back shell to protect the upholstery if the chair bumps into a desk or a workstation.