ReActiv, low-back design-perfectly balanced support for full zonal comfort. Height-adjustable, back-cushion-style lumbar support. Pneumatic seat-height adjustability accommodates various body heights. Synchro-tilt mechanism with seat slider for a full range of reclining positions. Tilt tension controls the rate and ease of recline. Upright tilt lock secures the chair in a full upright position. Adjustable arms put a little extra support right where needed.