Boss - BOPB996 Heavy-Duty Task Chair features a strong, 27" steel base with 2" dual-wheel casters for durable support and easy mobility. Adjustable arms on the chair can be moved up or down to ensure a perfect fit for most users regardless of height or the length of their arms. Pneumatic gas lift provides easy seat-height adjustments to help you find the personalized sitting style that suits you and your work environment. Spring-tilt mechanism allows you to change the angle of the entire seat relative to the floor and to transfer some of your upper body weight to the backrest of the chair. Task chair supports up to 400 lb.