Boss Office Products B8801-BE Executive Fabric Chair in Blue Passive ergonomic seating with built in lumbar support Upright locking positions Pneumatic gas lift seat height adjustment Adjustable tilt tension control Large 27" nylon base for greater stability; Hooded double wheel casters Passive ergonomic seating with built in lumbar support Upright locking positions Pneumatic gas lift seat height adjustment Adjustable tilt tension control Large 27-inch nylon base for greater stability