High Back Posture Task Chair with extra wide seat. Black polypropylene height adjustable arms. 2 Lever Syncro Mechanism and sliding seat lever. Black 5 star base and castors.Wide Waterfall Seat.\r\nSliding Seat.\r\nTension Knob.\r\nLumbar Pump.\r\nRatchet Back. 2 Lever\r\nSyncro Mechanism lifts up to have back free float and lock in desired position. Front lever lifts to adjust height of gas spindle. SLIDING SEAT LEVER (on left) : Lift up to slide seat into desired depth. Push down to lock.