Abstract: A chair includes a base having a hub, radially extending legs connected to and supporting the hub, a vertically extendable gas spring rotatably supported on the hub, and a hub tube sleeve non-rotatably fixed to the hub. A seat includes a housing that engages and is supported on the gas spring for vertical height adjustment, and a sleeve retainer rotatably connected to the control housing and extending downwardly therefrom. The sleeve retainer non-rotatably but slidingly engages the hub tube sleeve. A footrest is supported by the sleeve retainer. The footrest is non-rotatably and slidably connected to the base via the sleeve retainer and the hub tube sleeve, so that the footrest moves vertically with the seat when the seat is vertically adjusted, but does not rotate with the seat when the seat is rotated. The footrest is adjustably supported on the sleeve retainer, so that it can be manually adjusted to change the distance from the footrest to the seat.