BOSS Office Products BLACK TASK CHAIR/W ADJ ARMS, Mid-back styling with firm lumbar support. Elegant styling upholstered with commercial grade fabric. Sculptured seat cushion made from molded foam that contour to the shape of your body. Ratchet back height adjustment mechanism which allows perfect positioning of the back cushion and lumbar support. Optional adjustable height armrests. Large 27" nylon base for greater stability. Pneumatic gas lift provides instant height adjustment of the seat. Adjustable tilt tension that accommodates all different size users. Hooded double wheel casters. Upright locking position.