The chair includes a seat member and an adjustment member. The adjustment member includes a base, a positioning element, first pivot elements, first adjustment elements, each having a first extension segment and a first curved segment, second pivot elements, second adjustment elements, each having a second extension segment and a second curved segment. The chair has the first pivot elements located higher above the second pivot elements so as to create longer lever, greater torque, and steadier adjustment. By synchronizing the first and second adjustment pieces, the chair may be raised in a leveled manner requiring limited leeway.
