Features heavy-duty construction, comfortable seat (18"W x 17"D x 2-3/4" thick) with waterfall edge for improved circulation, a fully adjustable back (16"W x 10"H x 2" thick), resilient high density foam, easy-to-use pneumatic seat height adjustment, 360° swivel, and sturdy five-legged base with mushroom glides. Casters are optional and add 1" to 2" to height of chair. Contoured back with durable scuff-resistant back pan adjusts 2-1/4" vertically and 2" horizontally. Model 5000 features a five star reinforced plastic base. Model 5500 features a wider five star reinforced plastic base with an 18" adjustable chrome footring. Models 5200 and 5600 feature a 16-gauge tubular steel base with scratch-resistant, baked-enamel black finish and a sturdy 19" welded chrome footring that reduces pressure on thighs and promotes better circulation. BIFMA Class 1 rated Olefin fabric resists fading, pilling, punctures and moisture. Meets flame retardant standards of California Technical Bulletin 117. Standard Colors: Black, Gray, Royal Blue, and Navy Blue.