The Big and Tall series of the Space chairs have generous sized seats and backs both in width and depth - Seat Bottom Thickness: 4.5" Features include a mid-pivot knee tilt with adjustable tilt tension and two-way adjustable arms with soft polyurethane pads Also has an extra heavy duty gunmetal finish base with oversized dual wheel carpet casters Overall size: 28.75 W x 27 D x 42.5-45.5 H; Seat size: 21.75 W x 21.75 D x 4.5 T; Back size: 21 W x 22 H Approved for commercial use - This chair meets or exceeds ANSI/BIFMA standards Built to accommodate the larger user; supports up to 400 lbs. Breathable double Air Grid back with adjustable lumbar support.