Long-lasting Ergonomic Comfort. Ergonomic design provides relief from backaches, tension and muscle strain. Deeply tufted 100% nylon upholstery over 2-1/2" padded seat and back cushions gives firm support. Fingertip-control pneumatic height adjustment and swivel/tilt makes positioning simple. Seat is 19"D x 19"W and back is 18" sq. Height adjusts from 28 to 31". Heavy-duty adjustable foot ring supports legs and feet. Five blade base for maximum stability. Easy-rolling dual disc casters for complete freedom of movement. Easy assembly. Also available, optional stool glides can replace casters for stationary use.